... sizes: 16*16, 25*25, 25*40,50x50, 1) cable trunking accessories ,2) inner trunking ,3) "T" SHAPE Channel ,4)angle bend, outter ... ,good fire- resistant,good combustion-resistance3)Not rust occurs like metal pipe4) PVC conduit pipe with no smell attracting to rent ... ,control box , switch box or general service box 2012 good quality cable trunking