The average kayak seat is designed to fit the largest rear end that would likely fit in the boat, otherwise that kayak would be useless to those with a big rear end.
The Sweet Cheeks 200 allows your rear end to form a butt imprint down deep, creating a bucket that surrounds you in back, to the sides, and on both sides of your legs. Low spots are filled in, high spots are taken down, and all of the areas that aren't normally supported are suddenly supported.
The Sweet Cheeks 200 offers a 100% comfortable wedge in the front, made by your legs and crotch, that prevent slippage forward too. The back of the seat meets up with the backband in the exact right spot, so your tailbone is protected by foam, and the back of your rear end is firmly supported with the rise behind you.
How does it work? Got to love the bean bag concept for adjustability and firm support. When you are getting into your kayak with the Sweet Cheeks 200 for the first time, you'll get in after you inflate it about 4 breaths worth. When you sit on it the air will rush out of the tube, while the beans rush around to find a place to go until the air is mostly out. To "lock it in" for as long as you like your setup, simply suck the remaining air out, It is a perfectly locked down seat pad that won't slip around on your seat.
The bottom of the pad is made of Velcro hoops and it stays firmly in place on the Velcro in your kayak. Special set-ups: Want to be higher up in your boat- no problem. Jackson added more beans than necessary and made it oversized so the beans have a place to go. Simply blow air in it, move the beans under your butt cheeks, and suck most of the air out before you get in the boat. Get in, wiggle around just a little to make it comfortable, suck the rest of the air out and you will find yourself 1" higher.
Want to be lower and really have a deep bucket? Blow lots of air in it, get in and wiggle around while the air is being forced out. When the air is out, lift your butt off the seat while staying in the boat, blow two or three breaths of air in, and sit down again, wiggling around to get the beans to really form around you and move from under your butt.
Do this as many times as you want until you are the height you want to be (usually don't need to do it more than three times unless you want to be completely on the bottom. What does is cost you to have the best seat you have ever had?