I've had a lot of scrap pieces so been turning out bottle stoppers, have a bunch of burl pieces I think will be quite interesting but before I use them I'm trying to find the best stoppers, where to get them. I have a batch from Amazon they ware useless must be metric they are threaded differently than the standard. Got some from Penn State but after making several I found they did not fit securely in a wine bottle neck. I have one from Craft supplies USA haven't used it yet but it looks the same as the Penn State. Are there differences in the stoppers that much, the silicone seal on them barely fits into the neck turned upside down they just fall out. New to this I just ordered a bunch of useless stoppers thinking they are all the same.