Unused (new old stock) Maska SK QD bushing for synchronous drive, in original box (no labels on box). ID 1/2". OD 3 7/8". Three 5/16" UNC threaded holes; three 3/8" UNC threaded holes. See Baldor-Maska brochure for further specifications: http://store.kgpowersystems.com/Maska-QD-bushing.pdf