The Prmko 434 RL Automatic Door Bottom is a high-performance door seal that is designed to automatically seal the gap between the bottom of a door and the floor when the door is closed. This helps to prevent drafts, dust, and noise from entering the room. The 434 RL is made from durable aluminum and features a black sponge EPDM insert. The EPDM insert is soft and flexible, allowing it to conform to uneven surfaces and create a tight seal. The 434 RL is also sound tested to ASTM E90 standards, meaning that it can help to reduce noise levels in a room.