Flexible, can be used for many applications Thermoplastic construction that will not rust or conduct electricity Built in cable clamps to hold wire firmly in place 6 knockouts for easier wiring Use with Blank Cover HB1BL 1024-0752, Toggle Switch Cover HB1SW 1024-0737, Duplex Receptacle Cover HB1DP 1024-0729 or GFCI Cover HB1GF 1024-0109 UL listed E42728 and two hour fire rated for walls and ceilings Grey PVC 18.4 cubic inch 1-7/8 inch x 4 inch x 2-1/8 inch