snippet: <br/> Solid aluminum <b>Spacer Ring</b> used when installing our N666 Bullet Resistant Speak-Thru in glazing less than 1-3/16" (30 mm) thick. Depending on the thickness of the glazing material, Spacer Kits include either one or two rings. A Glazing Thickness Range Chart is available.<br/><b>SPECIFICATIONS:</b><br/><b>Material:</b> Aluminum<br/><b>Finish:</b> Brushed Aluminum <br/><b>Instructions Included</b><br/><p>.</p><b>Stainless Steel Advisory:</b> Although Stainless Steel is resistant to corrosion, it is not rust or stain proof. CRL recommends periodic maintenance to help maintain its factory finish. For more information, view the Stainless Steel Disclaimer found in the Technical References section below. (Page 1)