Although any brand of 23 GAUGE HEADLESS PINS are compatible with your Grex pinner, Grex pins are highly recommended due to the optimal tensile strength of the steel used. Some "aftermarket" pins are so soft that they will actually deflect in cedar and pine. Others will crumple on the surface of your workpiece because they do not have the stiffness to penetrate maple or oak or other hardwoods. Using poor quality pins can cause jamming and damage to your tool because their tolerances are not controlled or they have excess glue drips all over them. Some other pins are OK for softwoods and softer hardwoods like cherry but not for real hardwoods like maple and equatorial hardwoods. Grex pins really are the stiffest pins on the market. Because 23 gauge pins are extremely fine, using quality fasteners is much more critical than traditional finish nails such as 18 or 16 gauge brads.