Kubotan

A Kubotan is a self-defense keychain weapon developed by Sōke Takayuki Kubota in the late 1960s. It is typically no more than 140 millimetres (5+1⁄2 inches) long and about 13 mm (1⁄2 in) in diameter, slightly thicker or the same size as a marker pen. The material is usually a hard high-impact plastic such as Lexan. The body of the Kubotan is lined with six round grooves with a screw eye or swivel and split ring attachment at one end for keys. The term is a genericized trademark.