1/4 Inch 316(A4) Stainless Steel Finishing Cup WasherCountersunk washers are bowl shaped to allow flat or oval countersunk head screws to lie flush with the work surface and to create a more professional finish. Their recessed shape also prevents the screws from damaging soft material. Countersunk washers are often used when installing or repairing wood trim to create a smooth finished appearance over and around the fastener assembly.