These kits retrofit on V1 through V5 windlasses to allow for manually raising the anchor using a standard winch handle. They are a particularly prudent accessory if you sail in remote areas.

There are several versions of manual recovery adapters available, depending on your windlass model.
There are models for V1, V2, and V3 windlasses manufactured before 2008, and different models for FastFit V1-V3 windlasses manufactured after 2008. (2008 was a transition year, so you'll have to visually check your windlass for the motor attachment method; see below.)
There are also separate manual recovery adapters for the V4 and V5 windlasses. (These adapters also fit the, now discontinued, Concept 3 windlass.)

In the newer FastFit windlasses, the deck unit is attached to the gearbox with a conspicuous hinged clamp
On older V-Series windlasses, the deck unit attaches to the gearbox with bolts, in the traditional manner
There are separate kits for low-profile gypsy-only windlasses, and for windlasses with a drum (capstan) as well as a gypsy