Linear motion lead screw micro rail. The bottom rail include Arca Swiss compatible dovetail that works with Arca Swiss type clamp while the slider is equipped with quick release arca type clamp. Clamp can be oriented in 4 different positional in 90 degree increments. Camera to subject distance can be adjusted in fine increments. Lead screw delivers 1.06 mm of travel per full revolution but digital scale let you adjust positioning with 0.001 inch (0.025 mm) increments. Fast positioning can be done by pressing slider release button and slide the slider to required position. The digital scale allow direct conversion between metric and imperial reading and it can be set to zero at any position. Maximum travel distance 4.00 inch (101.6 mm). Macro rail use Self Aligning Linear Sleeve Bearings. Virtually maintenance free, they have a nonabrasive, chemical-resistant PTFE liner that doesn't require added lubrication. Shell is aluminum with a 0.002" thick ceramic coating for added corrosion resistance. Temperature range is â€“400Â° to +375Â° F. Rail will work in 90 degree orientation (perpendicular to the ground) with load up to 10 lbs. When rail is in horizontal orientation (parallel to the ground) it can hold up to 15 lbs.