Rimless Ultra Clear Tanks by Ultum Nature Systems These rimless aquariums are carefully crafted using 91% clarity Diamant glass, a highly transparent extra clear glass with very little residual green color. The low iron content in the glass provides uninterrupted crystal-clear visibility. The 45° mitered edges are bonded together using high-performance German silicone specifically designed for aquarium construction. Each Ultra Clear Tank comes with a black leveling mat. Why UNS Rimless tanks? 45° Mitered Edges 91% Clarity with Diamant Glass High-Quality German Silicon Free Black Leveling Mat Size Chart Guide Model Size Glass Thickness (mm) Volume (Gal) 16 C 6.29 x 6.29 x 6.29 in 16 x 16 x 16 cm 5 1 20 C 7.87 x 7.87 x 7.87 in 20 x 20 x 20 cm 5 2.1 25 C 9.84 x 9.84 x 9.84 in 25 x 25 x 25 cm 5 4.1 30 C 11.81 x 11.81 x 11.81 in 30 x 30 x 30 cm 5 7.1 40 C 15.75 x 15.75 x 15.75 in 40 x 40 x 40 cm 6 16.9 45 C 17.72 x 17.72 x 17.72 in 45 x 45 x 45 cm 6 22.8 50 C 19.69 x 19.69 x 19.69 in 50 x 50 x 50 cm 8 30.9 60 C 23.62 x 23.62 x 23.62 in 60 x 60 x 60 cm 10 57