I acquired my Rocker from Dalloz Fall Protection in September, 2001
The rocker consists of a movable lever and a fixed anvil sandwiched between two plates. The rear plate is a diamond-shaped stamping made from 4.3-mm anodized aluminum. A round 15.0-mm hole is cut in the top of the plate, and a larger 23.8 by 24.2-mm hole is cut in the bottom. The front plate is pear-shaped and smaller, lacking the projection for the upper hole. The front plate pivots on the lever mounting pin, and a notch in the left side of the front plate provides clearance for the anvil mounting pin.
The anvil and lever appear to be 14-mm slices cut from an aluminum extrusion and subsequently anodized. The anvil is attached to the rear plate by a round-head stainless-steel bolt that threads into a "nut" behind the rear plate. The "nut" is turned to form a rounded head; it has no flat surfaces for using a wrench. The bolt shaft is stepped, with an 8-mm diameter for 4.6-mm to engage the front plate notch, then 7-mm where it passes through the anvil and rear plate to the "nut." A coiled pin through the rear shell keeps the anvil from turning. The anvil itself is shaped like a low, wide isoceles triangle, with a cutout opposite the lever end. The lever is mounted on a similar bolt, but is free to rotate. A small spring forces the lever to the engaged position. A cutout on the rear side of the lever provides clearance for the spring.
The front plate has "CE0120," "EN353-2," "EN358,", "Rocker" and the Troll logo screened on the face. The inside of the rear plate has the "Sieg Heil" icon stamped between the hammer and anvil, and the serial number "00013" stamped to the side.
The Rocker is a compact, lightweight fall arrest that can also be used as a ratchet when hauling loads over a pulley. I'm not sure when the upper carabiner hole is necessary: the instructions don't show any cases where it is necessary.
I normally hesitate when asked to jump off a cliff to test fall arrests, so I'm not going to speculate on how well the Rocker works. Some informal testing suggests that the rocker can slide before it engages, but normally the slippage is less than a foot. The cases where I observed this were somewhat contrived (i.e., I held the rocker in a specific position and carefully dropped the load straight down) so I'm not too worried about this. I'm glad to see that the Rocker has no sharp teeth to cut the rope sheath.
The instructions on the Rocker warn against using it with soft or loose-sheathed ropes. The same warning should apply to other fall arrests as well; at least Troll tells people about this.
The Yates Rocker is similar, but has an addidional tab to limit the lever movement.
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©2007, Gary D. Storrick