The Xeros Bass End Pin Anchor functions perfectly, as long as you weigh enough to hold down one end of the strap. The ravages of time do not cause deterioration in the function of the Xeros, unlike strapless endpin anchors which rely on friction to stick to the floor. The strap also allows you to build up considerable momentum before throwing the Xeros by swinging it around your head (not yet an officially recognized Bassolympic event).
The D ring goes around the leg of your stool, and the sturdy retainer prevents your endpin from slipping forward on the floor.