What is "splitterring"

The Splitterring ( German compound combining Splitter (splinter or fragment) and Ring (ring)) was a fragmentation sleeve for the M24 and M43 stick grenades, developed by the Heer in 1942. German stick grenades had only a thin steel casing surrounding the explosive charge, which relied principally on blast for effect; the addition of a Splitterring gave it greatly increased anti-personnel fragmentation ability.