I wish I had known about this product sooner, it would have saved us a tonne of $$ and headaches with other sippy and travel cups. Such a simple and smart concept! We now use our canning jars as sippy cups and travel cups using the cuppow for our 2 girls (2 and 4 yrs). My big issue with travel mugs and sippy cups were if a part got broken or gunky (as they always get with sippy cup straws) you pretty much had to replace the whole thing and most sippy cups and travel mugs are not recyclable, so usually end up in landfill (I would keep the cup part anyway, but now I have a cupboard full of sippy and travel mugs with no lids!).