If you use sharpie pens when you perform.. You need one of the most popular accessory device used by professional magicians
Whilst it was initially designed for Double Cross here are a few gimmicks we are aware performers are using the Ultimate Sharpie Holder for -
Double Cross - Magic Smith
Super Sharpie - Magic Smith
Captive by Jimmy Strange
Fall - Banachek (Keeps the pen in ready to immediately remove and perform position)
Mental Pen - Joao Miranda (Allows the performer to have the pen upright with gimmick loaded and the cap loosely placed on top)
Coinvexed - David Penn (Pen is held upright in the holder to allow immediate locate the sharpie without needing to access the pocket)
When designing the holderm Matt needed the performers actions to look as natural as possible to load and unload a stamper pen and indeed when removing the pen so we had the pen sunk down so only a couple of centimetres sit above the pocket line.
For Sharpies like Double Cross,, With the black putty/sticky stuff always getting on my other gimmicks in the pocket it also became a concern for me that we had to keep it away from the performers shirt so the USH clip acts as a barrier keeping the distance between the shirt and the putty/sticky stuff.
When removing the stamper there is ink residue around the top of the pen that will be pushed against your shirt. USH protects you from that.