Construction: All windows are surface mounted - no obstruction or grooves in the counter. The bottom channel of vertical and horizontal sliding windows are fitted with a wool pile seal on the active sash and screen for counter contact. Material: Frames and glass channels of heavy type 6063-T5 aluminum extrusions. Bullet Resistant Glazing: Bullet resistant glass -- 1 1/4" bullet resistant Plexiglas, and 3/4" "Lexgard" is available in all stationary and registration window systems. Screens: Standard bright aluminum. Optional fiberglass, and bronze aluminum screens are available upon request. Finish: Anodized 204R-1 clear aluminite is standard. 215R-1 Clear, anodic hardcoat colors or white baked enamel is available for all windows on special order. Glass: 1/4" clear plate for windows not over 24" wide. For windows wider than 24", DSB glass is recommended. Glazing is extruded vinyl bead. NOTE: specify "Frames Only" or type of glass to be factory installed. Shipping: All glazed windows are packed in wooden crates. Unglazed windows are shipped in cardboard cartons. All shipping charges are "Freight Collect", unless prior arrangements are made.