US Patent 7329189 Flex drive connector

A flexible connector may include a tube having an open end and a lower end distal from the open end, an inner surface of the open end comprising a plurality of apices forming a substantially polygonal lower cross-section, an upper shaft having an insert end disposed insertably in the open end, an outer surface of the insert end comprising a plurality of substantially planer flats forming a substantially polygonal upper cross-section normal to the driven axis of rotation, the upper cross-section being substantially similar to the lower cross-section, and an elastic member disposed compressably between each of the flats and each of the apices.