The Heil PR 22 SUT is the same as the PR 22 UT with an on/off Switch.

The PR 22 UT has been designed for commercial broadcast, recording and live
sound reinforcement applications. This is a very rugged microphone, which makes
it ideal for professional use where exceptionally low handling noise is needed.

The PR 22 UT achieves its exceptional performance by using a special magnet
structure and a large aluminum 1 1/8" low mass voice coil assembly. A very
unique internal rubber suspension system has been designed to reduce
undesirable handling noise. Special attention has been paid to the phasing plug
assembly with equally placed ports that sense audio from behind the source
entering them out of phase. This produces a very linear cardioid pattern and
reduces the proximity effect while achieving the extreme articulation across
its smooth 50 Hz - 18 kHz frequency response. This new Heil element is usable
in extreme high sound pressure levels and is immune to overload conditions
making it perfect for vocals. It produces a beautifully smooth audio response
without the inconvenience of phantom or outside d.c. powering. This is one
great live vocal microphone that has finally replaced the `ball mic' of the
1970s.