With its small diameter marking head has become very popular for marking custom inspection symbols in all those hard to reach places. The plastic housing, it's marking head only 0.40" in diameter, allows the user to mark between components on a stuffed printed circuit board or within other confined spaces. UV ink is available for use on equipment or hands.Colors Available: Black, Blue, Red, Green, Purple, and Ultraviolet (ink can be used on equipment or hands).