The No. 15 ball grenade, also called the cricket ball grenade, was a grenade used by the British during World War I.
The No. 15 was a time-fused grenade. It was internally fragmented and incorporated a cast-iron body.
To light the grenade, the user had to remove a covering that was on the fuse, then strike an external Brock matchhead igniter against the fuse.
There were two types of fuses available; the five-second and the nine-second. The former was intended for throwing, while the latter was intended for catapults.
The No. 15 was one of the interim grenades created because of the problems associated with the No. 1 grenade. Unlike the others, the No. 15 had been created specifically for the Middle Eastern theatre of World War I, mostly for the fighting in the Dardanelles.
While crude, the No. 15 did well in the Dardanelles. In addition, it could easily be mass-produced; in September 1915, more than 200,000 No. 15s were created per week.