42 hand grenade, produced by the Polish resistance organization Armia Krajowa in occupied Poland during World War II.

[1] The name of the grenade came from Sidol, a metal-cleaning agent from Henkel sold in Poland at the time.

Later on the casing was purposely modelled after the bottle in order to allow for easier hiding of the weapon.

Until the end of World War II, an estimate of 350,000 R-42 were produced in Polish underground factories.

A large number of such grenades were used in the Warsaw Uprising and other battles of the Operation Tempest.