Ceramic tiles draw little or no advantage from sloped armour as they lack sufficient toughness to significantly deflect heavy penetrators. Indeed, because a single glancing shot could crack many tiles, the placement of the matrix is chosen so as to optimise the chance of a perpendicular hit, a reversal of the previous desired design feature for conventional armour. Ceramic armour normally even offers better protection for a given areal density when placed perpendicularly than when placed obliquely, because the cracking propagates along the surface normal of the plate. Instead of rounded forms, the turrets of tanks using Chobham armour typically have a slab-sided appearance.