PCS Company - Extra Large No-Twist Rectangular Mold Washers
Square Washers at Lowes.com
1 Square Plastic Washer 1.016 ID 2.000 OD 0.125 Thk Fiberglass USA - AMPG - Shoulder Screws, Shoulder Bolts, Sex Bolts, Flat Washers, Machine Screws and other fasteners
Hillman 4-Count #10 Black Oxide Square Washer in the Square Washers department at Lowes.com