"The Haoge HQR-400 Universal Quick Release Long Plate is a versatile Arca-style compatible rail with a laser etched reference scale in 1mm increments on both sides. It allows for easy point adjustment nodal.There are six holes at the ends of the plate for DIY L Plate or building other support systems.Double dovetail design with 400mm in length, supporting two cameras or flash at the same time.Features: Metal materials, CNC precision machining, surface oxidation treatment Double dovetail design, both sides can be mounted Arca-type equipment Compatible with a variety of digital cameras With standard interface 39mm AS, compatible with all Acra-Swiss Style quick release rigs Precise calibration accomplish the demand of locating quickly High quality aluminum alloy is used to ensure light weight but super high strength support. Four safety stop screws on both sides to prevent the camera from falling by accident. Specifications: Material: Aluminum alloy Color: Black Length: 400mm Compatibility: Arca-Swiss Standard Compatible with: RRS / ARCA-SWISS / KIRK / Wimberley / MARKINS / SUNWAYFOTO / Kangrinpoche / BENRO / SIRUI Ball head, clamp or pan head of AS standard interfaces (Note: the item can't fit RRS level release system) Package include: 1 x Haoge HQR-400 Quick Release Long Plate 2 x 1/ 4" 1x1/4 to 3/8 screws 4 x stationary pins 2 x Allen key (Note: Ball joint is not included)"