The IG 37s were manufactured from carriages of 3.7 cm Pak 36s (and the nearly identical Soviet 3.7 cm PaK 158(r)) and a barrel designed originally for the IG 42 infantry support gun.

As an anti-tank weapon it used a hollow charge shell with 0.5 kg (1 lb 2 oz) of explosives to penetrate up to 85 mm (3.3 in) with a velocity of 395 m/s (1,300 ft/s).

The gun has two distinctive features: the first is the large four-baffle muzzle brake and the second is the vertical sliding-block breech that was considered unusual for a Krupp designed gun.

The breech operates in a semi-automatic fashion, in that once the gun was fired the breech block would open and eject the spent casing and remained open to allow for rapid reloading.

The breech would then be closed once the next round was loaded and the gun was then ready to fire.