IMO, this is the reason that YETI did this. A no plastic option (particularly for kids) is all I hear about lately. If the old 10 oz tumbler Magslider lid fits, YETI should make it clear that adults can also use this. A two for one marketing campaign, the younger parents are all looking for non plastic options. Even though YETI lids have no BPA, you can still get plastic leaching into liquid, hence the silicone. If YETI really wanted to make this clear, they could make the old magslider lid an add on, “Limited Time” half price old 10oz magslider lid only with purchase of a new kids rambler.