The VL15-U is ideal for detecting fine powders,ordinary powder and granular materials and pellets.This “U” version is certified for use in dust explosionhazardous locations classified Class II, Group E, Fand G by Underwriters Laboratories Inc.The VL15-U is ideal for detecting fine powders,ordinary powder and granular materials and pellets.This “U” version is certified for use in dust explosionhazardous locations classified Class II, Group E, F and G by Underwriters Laboratories Inc.