This is a handy little screwdriver that can hold up to 17 bits.
The bits are held in place by 8 x 3mm disc magnets.

Magnets:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2054436.m570.l1313.TR0.TRC0.H0.XSuper+Strong+Cylinder+Disc+Magnets+8+x+3mm+Rare+Earth+Neodymium.TRS0&_nkw=Super+Strong+Cylinder+Disc+Magnets+8+x+3mm+Rare+Earth+Neodymium&_sacat=0