It's easy as 1, 2, ...
All you have to do is:
1. iron-on the Holster Patch on your desired item, and
2. sew around the edge of the patch for a more secure hold.
Ironing instruction for the Holster Patch.
Repeat step 5, and iron the inside of the shirt if necessary.
Final step: Sewing the Holster Patch.
Sew completely around the edge of the Holster Patch to ensure that, in the slight chance, that the holster may peel of due to age and washing.
Caution: Garment should be laundered and dry before patching.
Never exceed safe ironing temperature of the fabric being patched.