45 Minute Fire Rating A white bond coating is applied to each block for mortar adhesion. This block does not include pre-drilled holes and is not intended for crafting purposes. Actual Size: 5-3/4" x 5-3/4" x 3-1/8" Inch Minimal Privacy: This block is not ideal for areas requiring privacy Visibile Light Transmission: 84% Shading Coefficient: .65 Sound Transmission S.T.C. (dB): .41 Solar Heat Gain Coefficient: .66-.68 Thermal Resistance R-Value: 1.89 The 6x6x3 Clarity Glass Block from Seves Glass Block is a classic choice recognized for its crystal-clear design that has been trusted for generations. With no distortion or pattern, this block allows maximum natural light to pass through, creating bright, open spaces while offering limited privacy. Its clean and modern style makes Clarity ideal option to achieve a distinctive and creative design. Perfect for windows, walls, or partitions, this glass block brings a unique, inviting, and contemporary touch to any project