This is an old-style TAMA attachment. I bought it new about 40 years ago and used it for a few years to add cymbal holders. After that, I put it away and forgot about it. The larger hole is 20mm, and the smaller one is 12mm. Considering its age, it's in very good condition. There are no functional problems. For TAMA vintage enthusiasts! Please note that the price includes shipping, so please refrain from price negotiations. #TAMA #Drums #DrumSet #Adapter #Attachment #Expansion #Cymbal #Splash #Percussion