Canister
From ARRSEpedia
Ammunition type for artillery and MBTs.
Also sometimes called Beehive or flechette, it is like the old-fashioned Shrapnel round being a case filled with bits of metal and a bursting charge.
Unlike Shrapnel and modern proximity fused HE rounds, it bursts just beyond the muzzle of the gun, turning an otherwise normal tank main armament into a steroid-enhanced version of Holland & Holland's finest.
This wiki page will tell you more.
