So, in addition to many colors available for your choosing, we also have differing caps available for your bottles -- :D
At left, you'll see the choices --
-- the "bite-cap" and the "solid-cap".
The "bite-cap" is GREAT -- all you do to drink is flip up the bite-valve, bite on the nozzle and suck the water out -- there's a relief valve, so drinking is basically effortless, and you don't have to unscrew the cap to drink your liquid! Please note, it requires occassional disassembly and washing, as do most things!
Next, the "solid-cap" sort of is what it is -- if you want to drink, you need to unscrew the cap and you get liquid a-plenty! It is $3 less than the bite-cap.