The catch
PetSafe ScoopFree OpenSky
Wi-Fi is limited to 2.4 GHz, and there is no camera.
Side by side
PetSafe ZAL00-18120 vs Whisker Litter-Robot 4 Compared: Litter-Robot documents a three-pound minimum while OpenSky keeps an open top
Quick verdict
Go with OpenSky if you want an open top and ordinary clumping litter. Go with Litter-Robot 4 if you want a documented 3-pound minimum and records for four cats.
Before you buy
Why, and what it costs you
The catch
Whisker Litter-Robot 4 with Step and Waste Drawer Liners
A timid cat may still find the globe closed in.
PetSafe ScoopFree OpenSky
- Why pick it
- Ease a timid cat's change
- Handle a cat above 15 pounds
- The catch
- Wi-Fi is limited to 2.4 GHz, and there is no camera.
Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Why pick it
- Share among two or more cats
- Cover four cats
- The catch
- A timid cat may still find the globe closed in.
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What this page compares
See how PetSafe ZAL00-18120 and Whisker Litter-Robot 4 differ on cat and entry fit, litter and waste handling, and daily upkeep.
In practice, the choice depends on how the cat and the opening fit, which litter and waste system you want, and then the limits of your own setup.
Day to day
How each one fits your routine
A drawer claim made for one cat does not limit the box to one cat
OpenSky's current US page says outright that multi-cat households are supported, and the drawer interval of up to two weeks is stated for one cat. So if two cats need an open-top box, that interval is no automatic reason to rule out OpenSky. Pick it if the opening works for both cats and you can live with checking the drawer more often. Pick Litter-Robot 4 if its documented four-cat workflow and globe suit your household better.
Where this comes from
How much waste a drawer can hold and how many cats a box supports are two separate things. More cats can shorten the interval, and neither claim tells you the box can sit unchecked for a set number of days.
A high maximum weight tells you nothing about the kitten minimum
The up-to-33-pound description of OpenSky may matter for a large cat, yet it gives no minimum weight for automatic cycling. Litter-Robot 4 documents a three-pound threshold for automatic mode. When a small cat's eligibility decides the matter, check OpenSky's exact instructions and do not assume permission from its open design. Pick either one only if the operating limits and the real entry and turning space both suit the cat.
Where this comes from
These are separate checks: maximum supported weight, sensor eligibility and physical comfort. An open top can help a cat accept the box, but it does not show that automatic operation is appropriate for an underweight or very young cat.
Which one fits
Pick the situations that sound like you
Ease a timid cat's switch
On cat and opening fit, PetSafe ScoopFree OpenSky has on record “Check the maker guidance before enabling automatic cycling. Measure the cabinet against the available floor space” while Whisker Litter-Robot 4 with Step and Waste Drawer Liners has “3 lb automatic-cycle minimum. 22 in wide”. Measure your available space and mounting points, since this can be a hard fit constraint.
- PetSafe ScoopFree OpenSky
- Better fit
- Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Depends
House a cat above 15 pounds
For a large cat, look for a published weight range and an opening it can comfortably use.
- PetSafe ScoopFree OpenSky
- Better fit
- Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Depends
Share among two or more cats
On litter and waste system, the record for PetSafe ScoopFree OpenSky reads “clumping litter. Sealed waste path” and the record for Whisker Litter-Robot 4 with Step and Waste Drawer Liners reads “Clumping clay recommended. Plant litters typically unsuitable. Sealed waste drawer with manually removed liner”. For litter and waste system, this changes how much cleaning, filling or disposal you do by hand while you own the box.
- PetSafe ScoopFree OpenSky
- Depends
- Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Better fit
Entry stays open
Some cats won't go into an enclosed globe, and an open bed gets around that.
- PetSafe ScoopFree OpenSky
- Better fit
- Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Depends
Keep using the clumping litter I have
You can more easily stay with a familiar litter when the box works with a wide range of clumping litters.
- PetSafe ScoopFree OpenSky
- Better fit
- Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Good
Skip proprietary trays
With a reusable waste system, you don't depend on proprietary disposable trays.
- PetSafe ScoopFree OpenSky
- Better fit
- Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Depends
Option A
PetSafe, ZAL00-18120
ScoopFree OpenSky
Clumping litter is the documented fit, and waste goes into sealed storage.
- Best for
- Ease a timid cat's change
Facts we checked
- Cat and opening fit: Read the maker's guidance before you turn on automatic cycling. Compare the cabinet's size with the floor space you have
- Litter and waste system: clumping litter, with a sealed waste path
- Daily upkeep: Multi-cat design, two-week drawer example is for one cat
- For one cat, OpenSky gives a two-week example with an 8.5-liter drawer, and it supports single-cat and multi-cat homes.
Option B
Whisker, Litter-Robot 4
Litter-Robot 4 with Step and Waste Drawer Liners
Automatic cycling starts at 3 pounds, and the cabinet is 22 inches wide.
- Best for
- Share among two or more cats
Facts we checked
- Cat and opening fit: Minimum of 3 lb for automatic cycling. Width of 22 in
- Litter and waste system: Recommended litter is clumping clay, and plant litters are typically unsuitable. The waste drawer is sealed, with a liner removed by hand.
- Daily upkeep: Designed for as many as 4 cats
- Up to four cats are documented for Litter-Robot 4.
Spec by spec
Where they really differ
| Spec | PetSafe ScoopFree OpenSky | Whisker Litter-Robot 4 with Step and Waste Drawer Liners | In practice |
|---|---|---|---|
| Cat and opening fit | Check the maker guidance before enabling automatic cycling. Measure the cabinet against the available floor space | 3 lb automatic-cycle minimum. 22 in wide | Measure the available space and mounting points because this can be a hard fit constraint. |
| Litter and waste system | clumping litter. Sealed waste path | Clumping clay recommended. Plant litters typically unsuitable. Sealed waste drawer with manually removed liner. | Where litter and waste system is concerned, this changes how much cleaning, filling or disposal you handle yourself while you own it. |
| Daily upkeep | Multi-cat design, two-week drawer example is for one cat | Planned for up to 4 cats | Day to day, this changes how much cleaning, filling or disposal you do by hand while you own it. |
Trade-offs
What each pick costs you
With PetSafe ScoopFree OpenSky
- PetSafe gives neither a minimum cat weight nor a numeric limit for multiple cats, so check that your lightest cat and your household fit before you buy.
With Whisker Litter-Robot 4 with Step and Waste Drawer Liners
- Open rake boxes sit lower, since this tall body needs more vertical room.
Decision guide
How to decide
An open top with ordinary clumping litter favors OpenSky. A documented 3-pound minimum and four-cat records favor Litter-Robot 4.
Where they differ most
Cats up to 33 pounds are accepted by OpenSky.
What the figures mean
Automatic cycling on Litter-Robot 4 begins at 3 pounds.
The compromise
Litter-Robot 4 uses a globe, whereas OpenSky leaves the litter area open.
What this page can’t tell you
- No one can promise a cat will take to it.
- Odor strength follows litter, diet and how often you clean.
- Kittens that are very young could need manual operation.
- Sealed as it is, the LR4 waste drawer will not close or change the waste liner for you.
By the numbers
What the data shows
What we found across the automatic litter boxes we compare, plus the checked facts behind each finding.
Show the facts and the math
| Product | Needs it meets | Facts we checked | Sources |
|---|---|---|---|
| PetSafe ScoopFree OpenSky |
|
| |
| Whisker Litter-Robot 4 with Step and Waste Drawer Liners |
|
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Ready to buy
See today’s price and what owners say
Open either model on Amazon for the current price, customer reviews and delivery options.
PetSafe ScoopFree OpenSky
Ease a timid cat's change
See price & reviews on AmazonWhisker Litter-Robot 4 with Step and Waste Drawer Liners
Share among two or more cats
See price & reviews on AmazonEach link opens in a new tab.
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