Tascam 38 TSR 8 58 etc 1/2 inch Nab Hub adapter TZ-612
This is the standard NAB adapter for Teac/Tascam 1/2 inch machines.
These often break or become brittle with age, there should be a small piece of felt underneath to allow some give and take when putting on or taking off reels, this felt often is lost so you can screw the adapters down too tightly and as a result they break, They come in three colours black, brown and the later grey.
Second hand but fully functional
Sometimes these are marked with the TZ number but mostly they are plain there are some generic ones i have seen probably from the original mould, would love to source those if i could
other parts are listed else where.
Because of size goes as a packet.