After World War II, M37 grenades were modernized to use more modern fuses.
In the upper part of the grenade body there is a transition sleeve, through which the fuse is screwed along the axis of the body. The fuse is built according to the scheme with a rotating striker, which is thrown back by a lever and a check with a ring. The ring is pressed against the body by a spring. In the stowed position, the hole for the fuse is closed with a plastic plug. A solid iron body is used, due to which heavier fragments are formed during an explosion.