The life maxx pu dumbbells are protected with a polyurethane coating which protects the interior steel of the dumbbells as well as other equipment these might be used with these are professional dumbbells for expansive use in a commercial facility the dumbbells are made with steel making them sleek and compact to use the weight is displayed on the top bottom and side of each dumbbells making them easy to identify before picking up a weight this will prevent damaged weights and injuries by u