A cartridge plug for a CRUM-enabled ink or toner cartridge includes a CRUM device seated in an annular position, secured in a recess at a center of the cap. The recess is formed in a mounting surface of the cap that extends above a peripheral surface of the cap that the surrounds the mounting surface. The mounting surface is contiguous with the peripheral surface, being interposed by flexible walls that compress under load. The mounting surface is compressible under load by way of the flexible walls, and springs back to a resting position as a load is decreased.