Various thickness, ranging from 1-3mm, with 3M 300LSE industrial-strength self-adhesive backing on backside.
Bonds extremely well with metal, wood, plastics (even those plastics that don't bond well with other glues, such as Acrylic), leather, suede, fabrics, and many other materials.
Comes with fifteen sheets total. Four 1mm sheets, three 1.5mm sheets, four 2mm sheets, and four 3mm sheets. All measurements are approximate.