Remix of @LASWW's Gridfinity: Prusa PH2 Screwdriver - 1x4 but stackable and longer. Why longer? Well as the creator said in the original description:

Please note that there are several different versions of this screwdriver available. YMMV

The screwdriver I recieved in my CORE ONE kit was too long to fit in the original model. I'm guessing I must've received one of those 'different versions', so I stretched the case out a bit. The remixed model is now a 1x5 gridfinity bin; original was 1x4.