The Leofoto P Series Arca-Type Plates are designed for compatibility and stability, while providing a secure connection for your ball head and fluid heads. These are compatible with any arca-type clamp. Crafted from Type II Black hard anodized, 6061-T6 aluminum these base plates are built to last. In addition to the 3/8" mounting screw, there are two M6 anti-twist set screws to keep the head in place.