This is the Marcy Adjustable Dumbbell System: a 6-in-1 dumbbell that you can adjust up to 50lbs. It has a simple weight selector that lets you adjust weight quickly. It has cast iron plates with heavy duty plastic casing.
This dumbbell has a quick release locking system. It also has a chrome plated knurl textured handle. It measures 16.25 x 8.62 x 7.62″.