WW2 US Army M70F telescopic gun sight used in the M4A3 75mm Sherman Tank. This was used in conjunction with the 75mm M3 main gun. The Sherman's fire control system was improved by the incorporation of a direct telescope mount to the M38A1 gun mount. This prompted the creation of the fulllength gun mantlet to protect the scope. When these were retrofitted into older tanks, sometimes they would weld on armor over the scope, leaving a half armored mantlet.The M70 F telescope had 3x magnifications with 12 degree 19minute FOV.  An updated version of the earlier M70, it had superior optics, and a reticle that was updated for the newer gun.