Brady 139793 16mm Push Button Lockout Device, Standard, Transparent, 63.5mm x 50.80mm 64mm

Amazon

These locking devices prevent unauthorized use of push-button emergency devices For use with 16mm diameter pushbuttons Max. number of attached padlocks: 1 Risk: electrical risk, mechanical risk, Manufacturer: Brady Worldwide, Inc.

Radwell UK

(PRICE/EACH), 16MM CLEAR PUSH BUTTON LO W/ STD COVER