central hollow sleeve 52 which receives the upper end 48 of the shaft the latter has a pair of resilient fingers 54 having outwardly projecting stops 56 the knob has at its centre a small circular recess 58 thus when the knob is assembled to the shaft 40 the fingers 54 can enter the lower sleeve 52 and become compressed together as they pass through the sleeve once they reach the recess 58 however they can snap apart and the stops 56 will then lock the fingers 54 in place and so secure the knob 50 to the upper end of handle 40 the knob also has an outer downwardly depending circular flange 60 by means of which the user grasps the knob also its upper surface has a recess 61 in which a disc 62 is positioned which can hide the top of the handle and also hold a sheet carrying for example information corresponding to the relief surface 18b so that the user can quickly see what stamp he is picking up an intermediate stop member 70 is positioned between the flange 60 and the shaft 40 this stop member has an inner threaded cylindrical surface 72 which engages.