Length : 99mm
Diameter : 57mm.
Weight : 454gram including 156gram Comp. B
Fuze M217 (impact)
Green body with yellow markings.

This grenade was developed from the M26A1, but with different threads to fit the M217 impact fuze.
Square wire coil serrated on inside like the M26A1, but no tetryl booster is encased around the detonator tube.
The M217 impact fuze will self destruct after 4 seconds, if impact didn't. The text "impact" is stencilled on the lever.

The three photos below © Justin.

(this is the M57, missing the jungle clip)