THK-280-H-36-36-HD: HEAVY DUTY - ROOF BLOCKS (4), RECYCLED RUBBER, 3-M REFLECTIVE STRIP, 40-1/4' HGT CHANNEL x 36' PIPE SUPPORT CLAMPING AREA TOP & BOTTOM, (4) BRACKETS & FASTENERS (KIIT INCLUDING THK-280-AA-2-36 CJSTLMER ASSY) {BACK-TO-BACK CHANNEL}