Abstract: A locking device for two parts, mutually displaceable telescopically, e.g. a rod glidable in an outer tube, and including a washer with resilient serrations or teeth bent slopingly upwards out of the plane of the washer, which is retained in one part while its teeth engage the other part. An operating means is adapted for urging an annular lifting means into engagement with the teeth on actuation in one direction, so that the teeth are deflected out of engagement, allowing free movement between the parts, until they regain their engagement when the operating means is moved in the opposite direction.