Cantex EZ Box® 1-Gang Rectangular residential stud box with bracket, features steel stud construction. It measures 3-5/8-Inch x 2-1/4-Inch x 3-1/8-Inch. This 2-hour fire rated non-metallic box has capacity of 20-Cubic-Inches. It is suitable for masonry walls. Residential stud box is UL listed.