The Felsa 4014 watch movement is a manual wind mechanical movement that was used during the period 1928-. It operates at frequencies of 18000 or 20160 A/h, as suggested by Flume, although Gruen catalogs do not provide explicit information on this matter. The movement features a bimetallic screw balance and a Breguet hairspring. It is often or always identified as the Gruen 106. Differences between the 1067 and 1077 are not known, although it is speculated that they may indicate different base-plate shapes, such as round corners or octagonal.