9 hand grenades, also known as the "jam tins", are a type of improvised explosive device used by the British and Commonwealth forces, notably the Australian and New Zealand Army Corps (ANZAC) in World War I.

The jam tin, or bully beef tin, was one of many grenades designed by ANZACs in the early part of the First World War in response to a lack of equipment suited to trench warfare.

Incidents with the improvised form and the supply of superior grenades led to official withdrawal of the design.

Jam tin grenades were used as booby traps by ANZACs, by rigging it to a pressure trigger and leaving it under a body or other heavy object to keep it unarmed until it was disturbed.

During the Siege of Kut in Mesopotamia (December 1915–April 1916), the Royal Engineers in General Townshend's force improvised jam pot mortar shells to be used with improvised mortars devised from the cylinders of a Gnome 80 hp (60 kW) rotary engine (credit to Capt.