It looks like an ordinary throw, except the design is printed as outlines that you colour in yourself. Many come in at about 150 x 125 cm, with their own set of pens.
You pick a section, colour it in and come back to it another evening. Several people can colour at once, so it suits couples, friends or a quiet evening round the table.
Many designs are printed as white outlines on a black background, which gives a stained-glass look once coloured. Choosing the design is half the fun, so it is worth looking at the whole pattern first.
The question people ask most is about washing. Washable pens use water-based ink that, per the manufacturer, washes out in the machine, so you can start again. The care label sets the temperature and drying.
If you want to keep a finished piece, permanent fabric pens do the opposite: what you colour stays. It helps to decide before you start which parts should be permanent.
Two small tips before you start. Colour on a flat surface so the fabric does not stretch, and close the pens after each session so they do not dry out. Start with lighter colours; darker ones are easier to add than to take away.
It is an easy way to keep your hands busy while chatting or listening to music. It is also a popular Christmas gift idea, as it is still useful once the colouring is done.