I've owned the Motor Drive FN for the New F-1 I think since I got the camera around 1983, and since I rarely use 5 fps, I bought a slower, smaller, lighter, less battery consumptive Autowinder FN for a while, but I found that in single frame mode, the lag time was longer than the Autowinder, and the slow wheezy winding of the film to the next frame was annoying, so I went back to the 12-AA cell Motor Drive (I originally had the Ni-Cd pack, but when it wore out, I sold it for parts and bought the AA pack brand new, cash over the counter from Cambridge Camera circa 1993, figuring it was a better long-term solution) and sold off the Autowinder.