I acquired my Kong Block Roll from Inner Mountain Outfittersin 1999. The Kong Block Roll is 278 mm. tall, 79 mm. wide, and 35 mm. thick. Mine weighs 526 g.
The Kong Block Roll is a pulley attachment that fits onto the Kong-Bonaiti Modular Ascender. The Block Roll consists of a single pulley riveted between a stamped aluminum frame and a stamped side plate. It is rated for 15 kN (3300 lbs) when used as a pulley, and can handle ropes up to 16 mm. in that mode. With the Modular Ascender attached to form a hauling pulley, the rope size is limited to the range from 8 to 12 mm., and the strength rating is reduced to 5 kN (1100 lbs). Depending on how it is used, this may be too low to meet certain standards for rescue devices. I consider the Block Roll to be primarily a sport device, and for hauling packs and other equipment in caving and climbing situations, it will work well.
Although the Block Roll is part of a modular system, remember that there is a small bolt and nut that can easily be lost, so it may not be wise to expect to routinely attach and detach the block roll in the field where dropping the bolt may cause problems.