
The hole is large enough for a #8 countersunk screw, but the head does not fit completely flush. The magnetism is transferred to the (steel) screw head so things still stick, maybe just not as well. Screw #6 is flush. Also note that this alloy is somewhat brittle. So if you tighten them on uneven ground, they will break in half. However, they are very useful and very numerous. Subjectively, their strength seems to be the same as other neodymium magnets of comparable size; in other words, they are amazingly strong.

50Pcs Strong Neodymium Magnets With Hole & Mounting Screws - Heavy Duty Rare Earth Disc Countersunk For Locker, Tool Storage & Crafts
31 Review

MIKEDE Strong Neodymium Disc Magnets, 16 Pack Powerful Permanent Rare Earth Magnets With Double-Sided Adhesive, Fridge, DIY, Building, Scientific, Craft, And Office Magnets, 1.26 Inch D X 1/8 Inch H
40 Review

16-Pack Powerful Neodymium Bar Magnets | MIKEDE Rare Earth π§² Metal Magnets with Double-Sided Adhesive | 60 x 10 x 3 mm
35 Review

50Pcs Neodymium Magnets With Countersunk Hole And Stainless Screws - Strong Rare Earth Magnets Disc For Locker, Tool Storage, Crafts By MIKEDE
42 Review