These window regulator winder and cable repair kits are a cheaper alternative to the main dealer repairs. The window regulator is often only available as a full pre-assembled kit including the motor, sliders and all fittings. These normally cost hundreds of pounds so this kit containing the cables, pulley and brackets is a cheaper alternative often containing everything that you'll need.
The kit contains all the cables, the pulley for the motorised winder and the brackets that attach the glass to the sliders. These are the parts which most commonly fail.