Certalmid hand with a moveable two-way (sliding) thumb which is tipped with leather. All the fingers are rigid in a moderately flexed position. Made by Blatchford c. 1930.

Certalmid is a material consisting of Certus glue, muslin and celluloid. It was devised for making upper and lower limb sockets during 1914-18 war period and used in the development of prostheses for many years afterwards.