AB 644 RH
This is one of several applicable propellers used on the famous Sopwith Camel using either the Clerget 130 HP engine or a Bentley BR1 engine. The "AB 644" drawing number identifies it as "Air Board" (later Air Ministry) designation.
Length: 2590mm (8feet, 6inches)
WW1 Aero listing from a 1918 publication