A single handle for use with a grappler pivot to perform one-arm exercises. Used most frequently for one-arm T-bar rowing, but there are many other possibilities.
An Internet search of the terms "landmine training," "grappler training," or "angled barbell training" will reveal many of the numerous possibilities. This is one of the best ways to work excess fat off the abdomen and sides of your trunk (those stubborn "love handles" WILL finally succumb to the assault of consistent, prolonged, hard landmine training). It is no wonder that landmine training is exploding (no pun intended) on the fitness scene.