The see-through design of this special training handcuff allows you to view what is really happening when a handcuff is being locked, unlocked, double-locked, etc. It is a fully functional handcuff that lets the student see and understand the inner mechanical workings of a handcuff. Both the strengths and weaknesses inherent in all handcuffs become apparent. Also a useful tool for learning unconventional handcuff opening methods, such as the shim pick (see Handcuff Shim Pick).