An appropriate grind depends upon a blade's intended use and the material composing it. Knife manufacturers may offer the same blade with different grinds and blade owners may choose to regrind their blades to obtain different properties. A trade-off exists between a blade's ability to take an edge and its ability to keep one. Some grinds are easier to maintain than others, better retaining their integrity as repeated sharpening wears away the blade. Harder steels take sharper edges, but are more brittle and hence chip more easily, whereas softer steels are tougher. The latter are used for knives such as cleavers, which must be tough but do not require a sharp edge. In the range of blade materials' hardnesses, the relationship between hardness and toughness is fairly complex and great hardness and great toughness are often possible simultaneously.