DMM V-Twin

Technical details:

I acquired my DMM V-Twin from backcountry.com in 2008.

The DMM V-Twin is a notched belay tube. It is made from investment cast stainless steel. Mine is 56 mm. long, 42 mm. wide, 100 mm. high, and weighs 89 g. The slots are 35 mm. long and 16 mm. wide. The top of the Omega oval carabiner that I use for comparing belay tubes sits 16 mm. below the ends of the slots.

The V-Twin has two slots with ribbed V-grooves at one end. It also has a moderately stiff, plastic-covered cable keeper.

One sides of the V-Twin has a plastic inserts marked with "DMM."

Comments:

The V-Twin is and improved version of the ATC.that has V-slots that provide additional friction for belaying or rappelling. Each side of each notch has three rounded ribs, giving the notches "teeth" to grip the rope more effectively. These ribs are vertical so they do NOT act to guide the rope deeper into the slot as the teeth on the ATC-XP do. The notches do not have the narrow angle found on the Trango Jaws and its equivalents, so they do not create the same wedging action. For these reasons, I find the V-Twin to be less effective. On the other hand, the teeth on the ATC-XP provide a larger bearing area for the rope, which helps reduce localized heating.

The V-Twin is investment cast stainless steel which will make it more durable than its aluminum competitors, but according to DMM, the prime motivation was to reduce heating. Stainless steel has a lower coefficient of friction against nylon rope than aluminum does, especially if the rope is muddy. This means that the V-Twin should not heat as rapidly, and testing indicates that this may be true, but don't expect the V-Twin to remain cool after a long or fast rappel.

The logo on the side appears to be a thick plastic sticker. It does nothing, and may be removed. Some people tell me that this is there to keep from burning your fingers - you can easily guess my opinion about that, especially when the logo is only on one side. The V-Twin has a moderately stiff cable keeper that is quite adequate .The V-Twin is rigged like the ATC, with the V-slots on the brake hand end of the rope. Alternately, the V-Twin may be reversed to disable the V-slots.