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definition of a two-person load (200 kg) as defined by ASTM. Meets NFPA 1983 (2012
edition) for “Technical Use” as a DCD. Additional certifications: CE EN 12841 type C
and CE EN 341 class A. Strength (belay device) 14 kN MBS (3,147 lbf). Weight: 380 g
(13 oz).

ISC D4 Work Rescue Descender
The D4 Descender (Figure 47) manufactured by UK-based
ISC is a double stop device allowing for controlled descent at
different speeds. It is designed with an anti-panic feature
(Figure 48), in the event an operator pulls the aluminum
handle too hard. The device has an auto-lock function, which
is activated whenever the operator lets go of the handle. It is
designed to hold a static load of 4 kN (890 lbf) but to slip
between 4-6 kN (890-1349 lbf), so as to be able to be used as
a fall-arrest/belay device. The device is designed for loads up
to 240 kg (500 lbs), which makes the device suitable for a
two-person rescue without extra friction (e.g. such as a
redirect with an extra
carabiner). It is important
to note that the rated Figure 48- ISC D4 Descender ©
minimum breaking International Safety Components.
strength of the D4 is 16
kN (3,597 lbf). The D4 Descender can remain
attached to a rescuer’s harness for rigging and
opens with a push button. The button can be
operated with gloves, and is difficult to open under
load, decreasing risk of accidental opening. The
body is constructed of aluminum and the cam is
stainless steel. The D4 is ANSI Z359, NFPA T, and
Figure 47- ISC D4 Descender handle EN12841 certified. Weight 652 g (23 oz).
position functions.

Figure Eight

Although once a very popular friction device in technical rescue, the Figure Eight
(“Rescue Eight”) has lost its acceptance as a rescue DCD with the development of
much more versatile and appropriate appliances. It is shown here for comparison
only and is no longer considered a recommended tool for rope rescue. This
classic friction device is an efficient personal descender, however it does not provide
the necessary utility required to handle a rescue load. The device is loaded by feeding
a bight of rope through the large hole and looped down around the outside of the small

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