Primary use of these foam mandrels is for sanding organic shapes - especially concave ones which are difficult to sand with standard sanding tools mostly made to best handle flat surfaces. You may use these mandrels with batery powered drill or screwdriver, but I would reccomend a Makita angle drill.  Works perfectly for PowerSanding carved bowls as well as on a lathe when the workpice is turning. Sanding is more effective this way than with a woodturning sanding handle for holdind mandrels.

Either way you best use one of these especially for deeper bowls or vases or when you are sanding a turning object with an uneven / natural edge or rectangular bowls. Better to keep finger as far away as possible :)

Woodturning foam bowl sander set includes:

1x FREE hard 50 mm EVA foam mandrel
1x medium 50 mm EVA foam mandrel
1x medium 75 mm EVA foam mandrel
1x hard 50 mm EVA foam mandrel
25 pcs of 50 mm sandpaper discs in various granulations
10 pcs of 75 mm sandpaper discs