Abstract: A bowling ball insert has an outer sleeve and an inner sleeve (or solid), with the outer sleeve having a pair of vertical channels that are open at the top, and a pair of horizontal channels extending perpendicularly from the vertical channels, with the two vertical channels having different widths. The inner sleeve (or solid) includes tabs that are sized to fit in the outer sleeve channels, with at least one of the tabs being sized to fit in one vertical channel but not in the other vertical channel. The outer and inner sleeves additionally include a floor that is open at the center to allow access to the ball through the insert. The inner sleeve has an upper lip to provide a controlled insert depth in the ball. The horizontal channels may include a detent to lock the inner sleeve in place after it has been inserted into and rotated within the outer sleeve.