Why plug in a cable if you can pop a wireless transmitter into your go-to microphone? Snap-on transmitters are part of specific series which will also include a matching wireless receiver.
Turning an XLR Vocal Microphone Into A Wireless Microphone
Most standard vocal microphones are connected to a mixer via an XLR cable. If you’re tired of using cables, you basically have two options: you can either replace your microphone with a complete wireless handheld microphone system, or you can browse this department for a compatible snap-on transmitter. Bear in mind that if you're going for the second option, you'll also need a wireless receiver.
For Dynamic Microphones Only
Snap-on transmitters are generally only compatible with dynamic microphones. That's because almost all condenser microphones require power which a snap-on transmitter simply can't supply.
Additional Snap-On Modules for Wireless Microphones
Shure and Sennheiser offer various different series of wireless microphone systems that include snap-on modules. Have a scroll through what's on offer and if you find a snap-on module that comes from the same series and uses the same frequency band as your current wireless system, chances are it's compatible and can be used to expand your set-up.
Receivers and Frequencies
If you're going for a separate snap-on transmitter, then you'll want to make sure that the frequency it operates on matches that of the wireless receiver you'll be using. In most cases, the frequency band is indicated by (a combination of) letters or numbers (e.g. 'S50' or 'A'), which makes it easier to match transmitters and wireless receivers from the same series.