Very squishy they are, I like them for that and the price and they're not top heavy. Useful.I picked up some of the YFTK silcone bottles, they're much thinner than the Sunbox / Infinity Cappy V4's and quite a bit squishier (to use the tachnical term). I'm not 100% convinced but at the price they'll be worth experimenting with - If I ever get round to it...