This descender consists of a fixed plate in the rear and a pivoting plate in the front with two bollards and an autostop assembly consisting of a cam, handle, and connecting arm. The plates are each 2.8 mm. thick. The pivoting plate is stamped with a decorative line running down the left side and around the base off the hook, and then back to join itself near the top of the safety.
Starting at the top of the fixed plate, the autostop cam is mounted on a shoulder rivet near the top. The head and shoulder of this rivet fit into a notch in the pivoting plate.
The upper bollard sits 41 mm. lower, where it is riveted through its center. This bollard is made from aluminum alloy. It is 44.7 mm. in diameter and 16.7 mm. thick. A 2.8 mm deep milled channel in the bollard fits around the fixed plate to prevent rotation. There is also a milled recess to provide clearance for the autostop assembly connecting arm. The rope groove is U-shaped, 9.2 mm. wide, and 5.5 mm. deep. The pivoting plate has a second notch that engages a shoulder area on the mounting rivet. These notches provide support to keep the pivoting side plate from bending open during descent.
The lower bollard is 42 mm. in diameter, 13.2 mm. thick, and made from stainless steel. Its form is that of a circle truncated by two chords. The lower bollard rotates on a shoulder rivet attached to to the fixed side plate about 56 mm. below the upper bollard. This bollard has a 3.5 mm. deep, 9.2 mm wide V-shaped groove on its circular peripheral arcs. There is a a washer separating the lower bollard from the pivoting side plate.
A handle assembly mounted on the outside of the fixed side plate rotates on the same rivet as the lower bollard. The friction from the passage of the main rope causes the lower bollard to rotate, rotating the handle and pulling the connecting rod down. This pulls one end of the the autostop cam against the rope above the upper bollard, thus slowing the descent. The handle is used to keep the cam disengaged during normal descent, but pulling the handle too far brings the other end of the autostop cam against the rope, again slowing the descent.
A split pin pressed into a hole in the pivoting side plate engages an arc-shaped groove in the lower bollard. This forces the bollard to turn when the side plate is opened fully. This, in turn, rotates the handle, pulling the connecting arm down, and forcing the cam against the rope.
The attachment point is a 16.3 by 27.6 mm. oval hole near the bottom of the fixed plate. The hole is oriented vertically. The pivoting plate has a hook with a spring-loaded plastic safety.