G'day CJ, yes the 750 ml Plastic bottles seal perfectlyand unlike the glass bottles you can even put the cap back on a half bottle to drink later. Bottles re-usable countless times, you just buy new caps. The caps have like a seal ring that separates when you remove to pour. The Bottles usually come in boxes of 15. I use a stainless steel fermenter for a perfect seal (better than plastic one) and a "bottle Tree" to drain bottles after rinsing. (Pictured) I usually get 28 x 750 ml bottled from a brew and it is way cheaper than 24 x 330 ml carton of stubby bots !