This is a W.J. Keating block — a wood shell tackle block built for naval and marine service in the admiralty pattern. The shells are ash, and the sheave is Tufnol, a phenolic laminate chosen for its resistance to saltwater and its low friction on rope. Wood is the economical choice for the shell; Tufnol is the premium material — at roughly ten times the cost of wood — specified where the application demands it.
What makes this particular block interesting is that it is still a live product. NSN 3940-00-521-2794 — BLOCK TUFNOL 2M1209 W J KEATING P/N K1990-3-1 — appears in our NATO Stock Number catalog under FSC 3940, Blocks, Tackle, Rigging & Slings. Alongside it are dozens of other WJK part numbers we have supplied over the decades: snatch blocks, double-sheave blocks, wire-rope tackle, and more. The part numbers have not changed. The demand has not gone away.
There is something worth noting in that continuity. Defence and marine supply runs on long product lifecycles. Equipment specified in the 1960s still goes to sea today, still needs spares, and still requires a distributor who knows where to find them. That is what we do.