GG: With the newer type bottles you don't use the seals anymore as the teats seal against the screw top properly and you only use the plastic cap to keep it all nice and sterile. The sealing caps are now primarliy used if you want to store formula or breast milk in a bottle and you then insert the seal into the srew cap before refigerating or freezing.

You will find the plastic lids have a much firmer grip on the top of the bottle and there have been numerous times I have dropped bottles and the lid has never fallen off. Give it a go trying to get the lid off with one hand I find it impossible and need both hands to open.