0.79"x0.79", on a mesh-mounted high-quality fiber glass net, nominal sheet size 13"x13", 4mm thickness, 20 sheets per box, approximately 23 square feet. You'll get Extra 2% discount entering this Sales Rep ID in the check out page: rk082407 Sizes: 0.4"x0.4"(10mmx10mm) + 50.00% 0.59"x0.59"(15mmx15mm) + 30.00% 0.79"x0.79"(20mmx20mm)