The included washers give strength to the attachment.
Should be attached only to dense materials that can withstand the strain caused to two nearby attching holes without tearing/unravelling. When used with fabrics choosing a coated fabric is advisable.
Material: nickled metal
Weight:12.5 g
Outer diameter: 18/19 mm
Thicness that stays between attached surfaces: 6.5 mm
Assembled thickness: 11 mm + attached materials