Good for long haul flights
Flights longer than about 3hrs are *extremely* painful for my rear end. After a bunch of research, I decided to buy the Purple Simply Seat Cushion for a trip to Asia this past summer (including a 7hr, 12hr, 15hr!, and several 2-4hr flights).  The cushion fit all the various airlines seats just fine and wasn't too bulky or heavy to fit in my "personal item" (stored under the seat in front of me). I also bought a Therm-a-rest trail seat inflatable cushion to compare / combine.<br /><br />By themselves, neither cushion was enough, so I ended up typically using both cushions together, which basically eliminated my discomfort! I was even able to sleep on some of the flights, which is unheard of for me.<br /><br />Even though it wasn't enough by itself, I give the purple a full 5 stars because their website advertises the "Simply Purple" cushion as good for a "Medium (4-8hr)" sit time and my long flights exceeded that.  I didn't want to go up to the thicker (and much heavier) Double or Ultimate cushions as I expect those would be too inconvenient to travel with. It might be possible to swap the "Simply" for the lighter "Everywhere" cushion and still be ok.<br /><br />I feel like I've cracked the code for long flights and this cushion will be along for the ride going forward!
Rating: 5 stars