The kunai was a lesser-known but useful tool in the shinobi (ninja) arsenal. It may have evolved from a trowel used for gardening or masonry work. Like most tools of the feudal period, many sizes and shape variations have been documented. The average kunai measured about 34-40 cm (14-16 in) but versions have been documented ranging from as short as 20 cm (8 in) to as long as 60 cm (23 in), in varying widths. One source suggests the tool should be the length of the user's forearm, plus 3 cm (1 in). The larger models are sometimes called dai-kunai. Most kunai have a flat, wide blade that could serve as a digging or boring tool, pry bar, chopping device, or as a functional weapon. The handle was often wrapped in twine or slender rope. If lashed to a stout wooden stave, one could create a makeshift spear or pick. Seen below are two larger-sized models made of oak for training purposes.