From Amazon
Spax – Universal Screw Countersunk Head Phillips Z 4Cut Full Thread Galvanized Passivated A2L – 1081020350123, 1081020350503
Powertool World
Spax-S 3.5 x 50mm Pozi Countersunk Screws ZY Box x200 Pcs
This product is also available at 1 unverified merchant.