Replacing wood nailers at the building perimeter with DERBI-Eliminailer-T increases the structural integrity of the roof perimeter, significantly reduces the risk of failure and helps protect the entire roof system from costly damages and blow-off. 5.2” DERBI-Eliminailer-T replaces three wood nailers and allows 5.2” of polyiso with a ½” cover board or up to 5.7” of Polyiso. Available in 4” and 5.5” flange widths.nd 5.5” flange widths.