Multi-gang boxes With concentric knockouts For concrete or masonry walls Application Concrete or Masonry wall Material Galvanized Steel Box Type Multi-gang box Construction Type Welded Cover Included None Knockout Options 1/2" and 3/4" Concentric Knockouts — Sides: 8, Bottom: 4, Ends: 6 1/2", 3/4" and 1 in Concentric Knockouts —