My order came in today (8/8 and 12/12 sizes) . I went for the smallest Flat Bottom screw size they had on each size (8/8-FB and 12/12-FB).

(8/8-FB)
Fits Screw Sizes: #6, #8, M3, M4
Fits Screw Heads: Pan or Round
(12/12-FB)
Hole Diameter: 3/32"
Fits Screw Sizes: #10
Fits Screw Heads: Pan or Round
I'll try them out and let you know how I get on
