4-Pack - Package of 4 Custom Extra Large Stainless Steel Washers, which fit under the low-profile survey stake to increase its visibility. Installs flush with ground so you can easily mow or drive right over them. Solid Stainless Washers, not thin metal with turned-down edges that will bend. These washers make the low-profile survey stakes even easier to locate but still not obtrusively noticeable to neighbors or someone walking by. Low-Profile Survey Stake purchased separately. This listing includes only a 4-Pack of the XL SS Custom Washers. Please note, these stainless washers are made with Austenitic Stainless Steel which is better protected against corrosion than Ferritic Stainless Steel. Magnets will not stick to Austenitic stainless steel, but a metal detector can find them easily. They have a 13/16" diameter hole in the middle.