These gym floor tiles are 900 kg/m3 density, 15mm thick, are commercial grade, perfect 1000mm x 1000mm square with beveled edges. There are many cheaper production mats in the market, which are produced from the low-quality binders, thicker grains, or from tires that are not recycled properly. Causing gaps, air pocket, or other damaging issues causing the mats to expand, crack, or break. Whereas, our floor tiles are tightly compressed rubber produced from recycled tires with fine grain and high-quality binder, which stop these tiles from having an air pocket and hence causing it to break or crack. These rubber tiles are shock-absorbent, anti-slip, and non-toxic and are also ISO 9239-1:2010 (international standard reaction to fire tested). Features Perfectly 1m x 1m square, 15 mm Thickness No damaging metal scraps Formaldehyde-free Recycled material form high-quality tires Beveled edge approx.