Draper Chalk Line Set RWS109, This chalk line set  contains a chalk line reel, 4oz (113g) chalk refill bottle. This is a 30mchalk line

Used by hard floor layers and carpet fitters to mark out the floor or carpet prior to the fitter cutting or laying. Carpet fitters may wish to mark up an intricate or tight cut where they are short of carpet. But the hard floor layer can use the chalk line to produce a series of chalk lines from which to work, checking how the pattern will finish without cutting into valuable flooring materials. It is always better to make a mistake in chalk!

This tool should make up part of the carpet fitters and hard floor layers tool kit.