Robinair (16913 Replacement Filter For CoolTech ID and CoolTech ID Plus Genuine Robinair Replacement Sample Filter for Nos. 16900 CoolTech ID and 16910 CoolTech ID Plus Refrigerant Identifiers The sample filter provides retention of particulates and oil mist suspended within the sample vapor Filter incorporates a red dye that indicates when replacement of the filter is necessary As soon as red spots or discoloration begin to appear anywhere on the white outside diameter of the filter element, THE FILTER MUST BE REPLACED Failure to replace the filter when indicated may lead to severe instrument damage not covered under warranty repairs