I have Reefs and several pairs of Tevas, but these are my go to flips. 2 grown adults can comfortable fit on the 43" one with no fear of it not being able to bear the weight. Its probably a plumbing gasket, its 2cm wide with a 11mm opening, and about 2. If you like music with bass than this speaker is not for you. Good for now. 4 Std. Really helped with my bad knees (3 dislocations and one knee surgery). Didn’t like it, it gives no instructions on use Truly disappointing, I really wanted these to work -- but I will be returning these tomorrow. I loved the colors.