Then just cut the flap off with a pair of sharp scissors, and use a black sharpie to blacken the cue edge?
Joey, I'm assuming you switched gears and are now discussing the chalk holder I use (ChalkShark), not the inexpensive cell phone belt holder I suggested.
Yes, the ChalkShark natively has two rare earth neodymium magnets -- one inside the belt holder, the other at the bottom of the rubberized holder/housing that holds the chalk.
I don't use the rubberized holder/housing at all. I just glue a small patch of steel -- e.g. the round knockouts from electrical boxes (that you pry out with a screwdriver to fit conduit or armored cable), or a small square cut out from a tin can -- glued directly to the bottom of the cube of chalk.
I found I don't need the strength of two magnets (it's too much, actually). The bond between one magnet (inside the belt holder) and the patch of steel glued to the bottom of the chalk cube is definitely enough to firmly hold it.
Plus, with no walls of that rubberized holder to get in the way, it allows me to completely use the cube of chalk, all the way down to the height of about 1/4-inch (any less than that, and the worn-down chalk itself is brittle enough to break). Then, I simply throw it away -- the small patch of steel has served its purpose and is a "throwaway item" to me. I go get a new cube of chalk, another electrical box knockout (or cut a small square from the bottom of a soup or coffee can), and glue it with either polyurethane glue or
Barge cement. (This cement, btw, is the cement used by table mechanics to glue the cushions onto rails, etc. It's extremely strong, and no, the strength of the rare earth magnet does not rip the bit of steel away from the bottom of the chalk cube.)
I hope that helps explain it?
Best,
-Sean