Pemko PDB411AE48 Full Mortise Acoustic Automatic Door Bottom with Black EPDM seal 48" long. This Pemko automatic door bottom consist of an 9/16" x 1-3/8" Clear Anodized aluminum case which surrounds a movable drop bar seal. The drop bar seal is actuated by a plunger which contacts the jamb as the door is closing, forcing the drop bar seal down against the floor or threshold. The Sponge EPDM provides an excellent seal to keep out draft, dust, moisture, insects, fumes, light, and sound. To achieve the best acoustical results: Minimum Drop 1/8" - Maximum Drop 1/2"; Effective Range 1/8" - 3/4". This Door Bottom can be trimmed as much as 2" in length. Screw holes are slotted for adjustment. For full mortise installations.