The Anthracite Grey Inaba Denko Slimduct Trunking is easy to install and adds the finishing touches to an air conditioning installation by covering up unsightly pipework or wiring to give a clean Anthracite Grey finish. This quality plastic trunking is fire proof and UV resistant, meaning it can be used internally or externally. This 100mm Duct range is for pipe sizes up to 3/4" and 7/8" with 13mm insulation.