Pet Carriers
Mr. Peanut's Diamond Series — 18 × 11 × 11 in, Double Expandable
Mr. Peanut's Diamond Series — 18 × 11 × 11 in, Double Expandable
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5 of the 9 airlines we track will take it under the seat on their published figures: American Airlines, Delta, United, Frontier, Allegiant.Footprint as published, height with at most one inch of squash. Check yours against the source.
Before you book
Airlines publish their own maximum size for the space under the seat, and no two are the same. No airline approves carriers — they publish a limit, and the gate agent checks whether the bag fits. Compare all three measurements above against your airline before you buy.
Check my airline18 × 11 × 11 inches at the gate. Two zip-out bays at the other end. The same carrier that has to squeeze under a seat for four hours becomes somewhere your pet can actually lie down once you are on the ground.
The measurements
- 18 in long × 11 in wide × 11 in high, closed. Clears the published under-seat footprint of five of the nine U.S. airlines in our guide: American, Delta, United, Frontier and Allegiant. The four it misses are Alaska and Hawaiian, JetBlue, Southwest and Breeze. Southwest is the one that surprises people — it is wide enough, but it publishes 8.5 inches of height against this bag’s 11. We would rather tell you now than at the gate.
- Two expansion bays that zip open on either side once you have landed.
- Recommended for pets up to 15 lb, best for pets around 16 in long lying down.
- Weighs 3.5 lb empty.
What it does well
- One-piece faux fleece bedding pad with fold-out wings that fill the expansion bays instead of leaving them bare.
- Premium self-locking zippers — the bag cannot be pushed open from the inside.
- Large open-air mesh windows on the top and all sides.
- Top and end loading, plus a luggage strap.
- Zippered mesh pocket for treats, medication and papers.
- Padded shoulder strap with thick metal connectors and a hand carry handle.
- Wipe-down composite nylon. Name tag holder, leash tether and seat-belt attachments.
- Leak-proof design and materials.
Compare the closed size, never the expanded size, against a cabin limit. The bays are for after you land.
Before you book: airlines publish their own maximum under-seat dimensions and they are not the same. Compare the measurements above against your airline's published limit before you buy — our airline size guide has all nine side by side.
How to measure your pet
How to measure your pet
Two measurements decide everything.
Length. With your pet lying down, measure from the nose to the base of the tail — not the tip. Add 2 inches. That is the interior length you need.
Height. With your pet standing, measure from the floor to the top of the head.
Your pet must be able to stand up and turn around inside the carrier. That is the rule every airline writes, and the one gate agents actually check. If your pet falls between two interior sizes, take the bigger one — but check its exterior against your airline first. A bag your pet fits in but the airline will not take is no use to either of you.
Shipping & delivery
Shipping & delivery
We ship within the United States only, from warehouses in California and Nevada. Orders placed before 1pm ET on a business day are handed to the carrier the same day; after that, the next business day.
Delivery is typically 1–5 business days depending on how far you are from the warehouse. Shipping is free on every order, with no minimum — you never pay for delivery. Alaska, Hawaii and Puerto Rico are included at the same price; allow a few extra days for those three.
You get a tracking number by email as soon as the label is created.
Returns & exchanges
Returns & exchanges
Thirty days from delivery, in the original packaging and unused. Email us and we will send you a return authorisation and the address for that warehouse before you post anything — a parcel sent back without one cannot be credited.
Wrong size is the most common reason people write to us, and it is the easiest to solve: tell us your pet's measurements and your airline and we will tell you which size to swap to.
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This pet carrier was perfect for traveling! My 15-pound dog fit comfortably inside, and the carrier fit perfectly under the airplane seat. It made traveling so much easier and less stressful. I’m really happy with this purchase and would definitely recommend it
This is a great kennel. My dog is 12 pounds and love the extra room. I have used the smaller one for years,but decided to upgrade to this larger version.Good quality and comfortable
So many choices to choose on the right travel bag for your furry family member; I will say this is easy to use! ESPECIALLY for long travel as your able to get both sides extended, Zipper quality is durable! Comfort wise is soft and cozy, sturdiness is definitely sturdy! And design is sleek and classy
Can’t say enough about this carrier. We were nervous about how our dog would fit for our flight. It was perfect! We opened one of the side expansions and he slept the whole way. It’s very well built and sturdy.
After trying many carriers for my 22 pounds cat, I decided to try this one, really high quality, meet the airline requirements, I really love that you can expand it and my cat was very comfortable.I HIGHLY RECOMMEND THIS CARRIER
The measurements come first
Sized before it is listed
Every carrier lists a length, width and height. Every backpack lists the back length and the weight limit it is built for. The numbers are on the page before you buy, not in the box after it arrives.
Shipped from inside the U.S.
California and Nevada. No customs form, no six-week wait. Most orders leave in a single parcel; where a kit is drawn from two different warehouses we say so on the product page.
Ask before you buy
Send us your pet’s measurements and your airline. We will tell you which size to order, or tell you honestly that we do not have one that fits.