Dual use! These lids function as both a straw hole tumbler lid, and also as a fermentation lid! The 10.5mm hole will accept any straw up to 10mm, and is also the perfect size for plastic 3 piece fermentation airlocks!
Attach with the included stainless steel band! Unlike normal Mason jar rings, this one will not rust with normal use and is dishwasher safe.
Made of food grade silicone rubber, these lid inserts are dishwasher, freezer, and microwave safe. Silicone is a safe, green, non-plastic (BPA free) material for food use that does not leach any chemicals.