anonymousOD 3 I bought this as an add-on to make my collapsible chair more comfortable to sit on. They even included an anti-slip guard so that it will not slip around when installed over the seat. The cushioning was adequate but I wasn't able to insert the cushion together with the chair into the carry-on bag as a whole unit. Perhaps it will be useful if this cushion had a little sewn in "hook/loop" so that I can use a keychain to loop it with the collapsible carry-bag to make everything portable. For now, I am using this as a back cushion, which also served as a back pain relief.