Plastics are being found in our bloodstream and are poisoning our waterways and oceans. Heat plastic and it gives off carcinogens--cancer-causing agents. So, it is insane to get coffee in a cup with a plastic lid from which to drink, both ecologically and personally. Silicone lids solve both issues. How delightful! I recommend these heartily. The price is reasonable. [Can't speak to sturdiness yet, not having used them enough, but they seem like a winner.]
Rating: [5 of 5 Stars!]