They are an acrylic stem, some in fanciful colors with swirls, that are sold for cobs (they could likely be made to work with other types of pipes) by Vermont Freehand. It seens there is more history to it with Vermont FH acquiring it from another company. I think a lot of people use these stems to "upgrade" and dress up a cob.Been meaning to ask, just what is a "forever stem?"
https://vermontfreehand.com/product/forever-stem-filtered/I've enjoyed my dealings with them, and met Steve (owner?) at Muletown Pipe Show in 2023. Bought the green one then.