The S-Mute "Multifunction Mute" with magnetic retention contains magnets in both the strait mute and plunger/cup sections. These super strong magnets allow the mute to hold together when in cup mute configuration but also allow the mute to be disassembled easily and quickly. Here are some precautions you should be aware of:
Implanted Medical Devices (Pacemakers, Defibrillators, etc).
Implanted medical devices are sensitive to the presence of strong magnets like those in the S-Mute "Multifunction Mute" with magnetic interface. You should not use the S-Mute Multifunction Mute with magnetic interface if you have an implanted medical device like a pacemaker, defibrillator etc. The magnet could damage the device or cause it to go into magnet mode. If you have an implanted medical device I urge you to consider the multifunction mute with threaded interface, which has no magnets.