Patented FrontlineTM drain inlet filters are your first line of defense against industrial pollutants in stormwater runoff. Available as a catch basin insert (CBI) or a trench drain insert (TDI), Frontline provides the best combination of performance and flow of any drain inlet insert on the market. Frontline is top-rated for the removal of debris; heavy metals such as zinc, copper & lead; TSS, oil & grease (hydrocarbons). Its flexible design fits under the existing storm grate in a drop inlet or trench drain configuration. Frontline is easy to install and maintain with off-the-shelf, replacement filtration bags.