Bump caps protect workers from minor impacts in environments that do not require hard hats or helmets. High-density polyethylene (HDPE) bump caps are lightweight, plastic caps that resist chemicals, moisture, and moderate impact. They typically have perforated vents that keep workers cool and pinlock suspensions that adjust the bump cap's fit. Bump caps can also resemble baseball caps. The plastic protective cap is hidden inside a synthetic fabric outer layer. These bump caps have a low-profile design and are breathable.