1 3/4" Mini 12-ga shotgun shells. Minibuck shot loads with 7 pellets of 4Buck and 4 pellets of 1Buck at 1200 fps. Low-recoil and a great choice for home defense.
"Works well in Winchester 1300 and FN shotguns. Remingtons and Charles Dalys may require some modification. Mossbergs require some elevator modification. There is some success with this load in a Benelli Nova."
--Does size really matter?