1/2 in. Paper-Faced Metal L-Shaped Trim, 8 ft. Used when wall-board is hung against suspended ceilings, beams, plaster, wood, or cement ceilings. Dimensions: A - 1/2 in., B - 15/16 in., C - 1 1/4 in., 8 ft. long. Benefits: Can also be used on untrimmed door and window jambs. Strong impact resistance. Forms superior bond with drywall compound. Reduces cracking along edges. Sheetrock® Paper-Faced Metal Corner Bead Brochure