This is the Jayflex Hyperbell EZ Curl Bar: a fitness tool that turns dumbbells into a curling barbell. It has 200lbs capacity, so you can attach 100lbs on each side. It comes with modular adapter clamps lined with foam for a secure grip.
This dumbbell curl bar lets you work your arms with less stress on your wrists. Hyperbell is comaptible with hex dumbbells, Bowflex SelectTech Adjustable Dumbbells (552 and 1090), CORE Fitness, Peloton, and other dumbbell brands.