I haven't had baby yet, so haven't used them - so can't judge from a practicality standpoint! I love that there is instructions on making using these easy - just fill the lid to 40ml with boiling water, and leave bottle in for 8 seconds to heat up! I love that you can use the cups beyond a bottle, as sippy cup, with purchasing another attachment, and it already comes with a lid to close it, so it's ready for carrying around puree's for Bub later too! I never wanted to use a plastic bottle with Bub, so I'm glad you've got your FB advertising working for you ;) and for us! I knew there were glass ones, but I would assume they would be heavy, and would be easy to smash, and they just don't have the same functionality as your bottles! Thank you for your creation and sharing them with the world :) A x