Product Description Vixen style metal rail bar mounting plate with dovetail fits all standard Vixen style saddles manufactured by any brand. Four 2.83" (71.8mm) slots are designed for mounting balancing equipment.0.25" (6.4 mm) wide slot accommodates M6 and 1/4" screws.Also, each slot has two 3/8" screw holes (M8 countersunk holes) and a 1.4" (35mm) spacing between each hole in the same slot and 2.53" (64.3mm) spacing between the two adjacent slots. There are 32 holes in total, 0.25"/6.4mm, spacing between each hole in the same slot is 0.79"/20mm, and between the two adjacent slots, there is a 1.55"/39.3mm spacing between the two screw holes in each slot.These holes attach a variety of devices with matching screws. Graduations allow you to find the exact position to mount your device for astrophotography, astronomical observation, night sky observation, and astronomical observation. Soft non-slip rubber pads increase stability and protect your device from unwanted scratches.The screw on the bottom can prevent the mounting plate from falling out. Specifications Model: QR009 Material: Aluminum Alloy Mounting Screws: M6, M8, 1/4", 3/8" Dimensions: 15.7" x 1.7" x 0.6" / 400 x 43.5 x 15mm Weight: 11.9oz / 338g Package Content 1 x 15.7"/400mm Vixen Style Mounting Plate 2 x 3/8 D Ring Screws 4 x 1/4" Hex Head Screw 4 x M6 Hex Head Screw 1 x 4mm Right Angle Hex Key 1 x 2.5mm Right Angle Hex Key