Oh, sorry about that. The "bouncing" 8.1cm round worked by having a small black powder charge in the nose which detonated on impact throwing the bomb back up into the air 2 - 4 meters where the main fuze (having been initiated by the impact too) went off causing this round to have an air burst effect making it more useful against infantry in the open.
One problem with it was it didn't work well on soft ground and the bouncing effect was somewhat erratic. The round was issued in small numbers operationally in late 1943 - 44 before being discontinued.