Phillips 093 zinc expansion control joints are manufactured from the highest quality solid zinc coil stock for superior corrosion resistance. An excellent product for interior or exterior applications, Phillips 093 expansion control joints relieve stresses of expansion and contraction across ceilings and wall areas. The opening is protected by plastic tape which can be removed after joint compound or plaster has been applied. Perforated flanges provide for excellent joint compound adhesion as the joint compound penetrates through the flanges to the wallboard for long lasting adhesion. The perforated flanges also allow for faster drying. This product fits standard 1/4″ openings.