Solid dumbbells. I like how they are more condensed than you typical rubber hex dumbbell in terms of length. A 100lb dumbbell is not super wide to the point that it’s awkward to bench and a 30 lb dumbbell isn’t so wide that it awkward to twist upwards while curling. The size seems similar to a nice commercial polyurethane dumbbell that you would use at a gym. The rubber grips are really nice as well. Definitely prefer it over metal grip handles.