Although a canopy which provided clear vision to the rear necessary for dogfighting like the F-86 was designed, production MiG-17Fs got a cheaper rear-view periscope which would still appear on Soviet fighters as late as the MiG-23. By 1953, pilots got safer ejection seats with protective face curtain and leg restraints like the Martin-Baker seats in the west. The MiG-15 had suffered for its lack of a radar gunsight, but in 1951, Soviet engineers obtained a captured F-86 Sabre from Korea and they copied the optical gunsight and SRD-3 gun ranging radar to produce the ASP-4N gunsight and SRC-3 radar. The combination would prove deadly over the skies of Vietnam against aircraft such as the F-4 Phantom whose pilots lamented that guns and radar gunsights had been omitted as obsolescent.