This is a magnetic disc 26" total diameter with a 9.25" uncoated exposed metal center, to which is bolted a 8.25" diameter hub using four bolts that pass from the other side of the disc. The hub is slightly more than 0.25" thick, with a 0.5" thick extension that is 0.5" wide and 6" outside diameter. There is a 3" diameter hole through the center of the disc for the hub; the hole is surrounded by four 0.5" diameter holes. A small paper blue dot is attached on the hub.
Identifying Numbers
Other number
59494-1
Written in black magic marker on the side opposite the hub.
Other number
83-138-01A
Written in black felt tip pen on the hub side and covered with some protective paint; this is the deprecated LLL accession number.
Other number
A2
Written in black felt tip pen on the side opposite the hub.
