Available fillers and additives give you the abiltiy to customize WEST SYSTEM 105 Epoxy Resin for your specific application.407 Low-Density filler is a blended microballoon-based filler used with WEST SYSTEM Epoxy to make fairing putties that are easy to sand or carve. Reasonably strong on a strength-to-weight basis. Dark red/brown. 12 ounces. For the suitability of fillers for specific applications, see theFiller Selection Chart.