500PLB The 500PLB is an optional accessory for the Infinix SCM mount kit. The 500PLB provides plenum-rated enclosure protection for cables and equipment housed above the mount. Features: -Large hinged door at top of box for easy access.. -Knockouts for .75", 1.0" and 1.5" conduit connections.. -Designed for easy relocation of mount without need to remove plenum box (safety cables can pass through plenum sides).. Specifications: -Color: white. -Dimensions: 5.125"D x 7.75"W x 13.25"D. -Weight: 2.2 lbs. -Knockouts: (2) .75", (4) 1.0", (4) 1.5". -Certifications: Conforms to UL Standard 1678 (ETL 3173417). -10 Year Warranty.