WEST System 404 High-Density Adhesive Filler is an epoxy thickening additive. We developed it for maximum physical adhesive properties in hardware bonding, or anywhere that high-cyclic loads are anticipated. Blended with epoxy, it makes an excellent gap filler or structural fillets. Use 404 High-Density wherever you need an especially strong bond. You can blend it into any WEST System 105 Resin/20X Hardener combination, G/flex Epoxy 650, or G/5 Five-Minute Adhesive. Blended with epoxy, it will cure to an off-white color.