This unique Co-Extruded setting block has a rigid Polypropylene top layer that effectively isolates the rubber block from the double glazed unit edge sealant. This eliminates the risk of plasticiser migration from the block to the butyl seal of the double glazed unit. This helps to prevent any chance of unit failure. Sold in 150mm pre-cut lengths, in packs of 100. This profile also incorporates an 8mm x 3mm drainage channel.