rappel devices
Descenders, or rappel devices, are designed to apply friction to a rope in order to control the rate of descent. They are attached to the caver through the master attachment point, which is usually a demi-rond maillon or Petzl Omni on a caving-style harness. Types of rappel devices include knots such as the Munter (or Italian) hitch, figure eights, tube devices, brake bar racks and bobbins. The general idea is that the rope takes a tortuous path through the descender and the friction that is generated helps to control speed, and ultimately this energy is dissipated as heat. The devices favored by cavers are the brake bar rack and bobbin. The most common forms of the brake bar rack are the 6-bar open-frame rack (J-frame), originally developed by John Cole in the 1960’s, and the 4-bar micro-rack. The most common versions of the bobbin are the Petzl Simple and Stop, which were originally developed by Dressler, also in the 1960’s. The advantages of these devices for caving are that they allow a wide range of friction control for varying conditions underground, they allow easy installation and removal from the rope without disconnecting them from the harness, they don’t cause a twist in the rope, and they are easy to lock-off for hands-free operations such as rigging, or mid-rope maneuvers such as changeovers, crossing knots, or crossing rebelays.
Bobbins
The preferred choice for use with a Frog ascending system. Favored in most of the world outside the US, and growing in popularity inside the US. They are lighter, shorter, and less bulky than brake bar racks, and they are generally faster to attach or detach from the rope, which helps when crossing obstacles such as rebelays, knots, or performing changeovers. They are smaller and have less mass than brake bar racks, which means they aren’t as good at heat dissipation, and they arguably don’t have the same range of friction control, so they are less suited to long rappels, and they aren’t recommended for anything over 100 meters. Bobbins are made by Petzl (Simple and Stop) and Kong (Banana, Pirata and Indy Evo). You may also encounter the discontinued SRTE Stop.
microracks
The most common version of the microrack has 4 bars - 2 are captive and 2 swing away from the frame - with one or two hyperbars. These are a lighter and shorter version of the traditional 6-bar J-frame Cole rack, and they are growing in popularity. They are a good alternative to a bobbin for use in a Frog system for cavers who are more practiced and comfortable with racks. They are made entirely of stainless steel so they last a long time, especially in muddy or gritty caves, and the bars can be flipped, swapped and eventually replaced. They are made by BMS, SMC, CMI and Kong.
Open-frame racks
The standard descender for indestructible rope technique (IRT) and the best option for long uninterrupted rappels in excess of 100 meters. Made by SMC, Petzl and CMI.
Petzl Stop (2019 model)
In 2019 Petzl has released a new version of the Petzl Stop, which borrows some design concepts from its other descenders, as well as the Kong Pirata. It is an auto-stopping descender that now has both bobbins made of stainless steel, but neither bobbin (aka pulley) is replaceable, and the price is quite high. Many cavers prefer the control and comfort of the new release lever over the old style Stop’s squeeze handle.
petzl Simple (2019 model)
Also in 2019 Petzl has released a newly designed Simple bobbin descender, but it has very few changes from the old design. The new model has identical and symmetrical bobbins (pulleys) that can be flipped or swapped to distribute wear, and so now there is just a single replacement part. The nuts on the new Simple are the same 13 mm size as the bolt head, which is the same as the wrench on the TamTam hammer, rather than the 14 mm nut on the old Simple. There is a larger oval slot in the rear plate for use with the new Freino-Z carabiner.
Petzl Freino-Z (2019 model)
This is a locking carabiner for attaching a bobbin to a harness master attachment point such as a demi-rond maillon or Omni. It is equipped with a friction spur for added control during a rappel. It is the world’s most expensive carabiner, it wears out quickly, and it causes accelerated wear to the bobbin, but it provides exceptionally good control and the ability to quickly and easily lock-off and unlock a bobbin. The Freino-Z was released in 2019 and replaces the original Freino, which was prone to cross-loading during certain mid-rope maneuvers.
Petzl Freino
The original Petzl Freino works with both the old and new Petzl bobbin descenders, as well as other brands (unlike the new Freino-Z, which only works with the new Petzl bobbins).