These adhesive backings can be used on wax seals. 3M adhesive is considered one of the best in the industry, making reliable seals you can count on. 20mm Round measures approximately 20mm or 0.78 inch, suitable for 20mm wax seals. Comes in multiples of 48 pieces. 25mm Round measures approximately 25mm or 1 inch, suitable for 25mm wax seals. Comes in multiples of 72 pieces. 35mm Obround measures approximately 35mm x 20mm or 1.3 inch x 0.78 inch, suitable for 35mm long obround wax seals. Comes in multiples of 60 pieces.