Description The Acoustic Door Drop Seals are designed for the gap between the door bottom and floor, it provides an excellent barrier to airborne sound and helping to ensure that the acoustic attenuation provided by a door set. A medium duty, concealed automatic door bottom seal that is mortised into the bottom edge of single action doors. It operates automatically by a spring-loaded mechanism, which lifts the seal clear of the floor as soon as the door is opened. The sealing gap in 3mm-13mm. Product Name Acoustic Door Drop Seal Material Aluminum Alloy + Silicon Rubber Dimension(mm) 14x34 Gap(mm) Min. 3 mm / max. 13 mm Standard Length (mm) 600mm,820mm,920mm,1070mm, 1220mm Seal Color Black, Grey Fixing Concealed, with supporting stainless steel escutcheon plates Cutting back length Nominal Seal Lengths Cuts back to Qty/Box 1220mm1070mm 30pcs 1070mm920mm 920mm820mm 820mm600mm 60mm380mm PackageDoor Drop Seal website:http://www.firestopchina.com/acoustic-and-drauht-seal/door-drop-seal/