The Omega R13.5SC is an open face calibre watch movement that features a pendant mounted on the movement. It incorporates various functions including a 60s (0.2s) and 30min pillar wheel, with optional settings for 30s (0.1s) and 15min, as well as 10s (1/30s) and 5min. The movement also includes an addition timer with a pusher, a flyback function, stem winding capability, a center second hand, a timer function, and a jeweled lever. This particular movement was commonly utilized in watches during the 1970s.