Instatherm® upper filter funnel used to keep viscous materials, such as polymers, in the liquid state. The low voltage funnel requires a variable output voltage controller such as 12324, 12323 or 12335 controllers. The central union and snap ring are PTFE. snap ring are PTFE. The interchangeable fritted disk is in the, 25 to 50 Micron range. The entire assembly can be taken apart for cleaning and the fritted disk can easily and economically be cleaned or replaced.