The Movcam Rosette Hand Grips with 15 / 19mm Adapter Kit from B&H is a quality-built set of two industry-standard-rosette items that will combine to outfit your camera rig with hand grips. The hand grips attach to the adapter and the adapter to the rods of your camera rig. You're free to attach one hand grip or both. Each hand grip is back-and-forth adjustable at the turn of a knob, and the adapter additionally features a 1/4" screw-hole for mounting 1/4"-20 accessories.
The adapter is compatible with both 15 and 19mm rods. The first are the more commonly used ones, and the latter are more often found in studio settings. The adapter mounts the rods and snaps tight on them by two flip-levers. The hand grips and the adapter then line up to each other by the rosette wheels of each, and then screw tight to each other by 1/4" screws, which you'll find on each hand grip and which you'll find convenient to work with as instead of screw-heads they feature knobs, the same kinds that adjust the hand grips back and forth.
Both the adapter and hand grips are made of high-grade aluminum, with the hand grips additionally featuring rubber handles. The set comes to you at a discount over the combined price of its two items sold separately.