The RST-V25 is a lightweight, 3-pound auto-braking trolley designed for zipline arrival speeds up to 20 mph. The trolley's durable wheel, brake pad and fail-safe braking system ensure automatic braking via friction for years of fun. Adjust the carabiner slot placement to set the speed for similar slopes and temperatures- no adjustments for rider weight needed. That's right- our auto-braking technology is not rider weight dependent and supports riders from 35 to 250 lbs. (Often lightweight zipliners arrive slightly faster than heavier zipliners.) Two wheel zipline trolleys account for 80% of all zipline accidents, earning them the industry nickname "death-sliders." Passive braking technology, found in the RST-V25, is service-proven, dating back to the first passive braking trolley our company designed and manufactured for the 2002 Park City Mountain Resort zipline. They've been in use there ever since with zero braking accidents. Testing is required (use a 35 pound weight) on your course for setup, so take time to determine the pin placements you need for yours (instructions included). We recommend periodic self testing and adjusting the carabiner slot placement with changing seasons and temperatures. For maximum safety, we always recommend a redundant spring system (like our parent-pending Barrel Springs) as an extra precaution, even with the RST fail-safe features. The RST features a rotatable brake pad; when the pad wear reaches a safety pin hole or the brake into the indicator hole (not shown), simply unclip the locking safety pin, rotate the brake pad 180 degrees, and replace the locking safety pin to renew the brake. Contact us to learn about brake pads with a greater coefficient of friction which will allow the RST to safely zip or traverse slopes near 35 degrees. RST's speak for themselves with safer arrival speeds and no zipliner retrievals.