Although most standard walkers and rollators have durable aluminum frames, there is a maximum weight capacity. Most have the ability to hold individuals up to 300lbs. There are some heavy duty models that can withstand much more. Bariatric walkers and rollators are specifically designed to withstand additional weight and are often manufactured using welded steel. These heavy duty models are made to hold 400 lb, 500 lb, and up to 1000 lb. See the page from 1800wheelchair.com that shows these heavy duty designs.