Padlock

Padlocks can secure bondage equipment

Lockable rubber corset

A padlock is a device for locking things together. In a BDSM context, it may be used for securing chains, metal and leather bondage equipment to make them escape-proof, and for securing an item of clothing so that it cannot be removed. (See for example "Lockable shoes" under Shoe fetishism.)

If several padlocks are used in a bondage session, it is advisable to get a set that all open with the same key, so that the padlocks can be removed rapidly without excessive fumbling for keys. Alternatively, each key and padlock should be labelled.

This article on "Padlock" incorporates text from from Wipipedia.