1.combustion proof,fire resistant 2.special lock,installing more easlier 3.according to the customer in colour and performance Product feature:our combustion-proof pvc trunking has strength tenacity,and are combustion-proof,fire proofing,damp proof,acid-resistant,age-resistant.ModelSize(mmxmm)AIB15 15/1x17AIB22-1 22/1x10AIB22-2 22/2x10AIB25 25/1x17AIB40 40/2x17AIB50 50/3x20 pvc duct