A specialty Foley catheter is determined by the tip configuration, number of lumens or channels, and the size of the balloon. Specialty Foley catheters may have tip types such as Councill, Coude, Olive, Couvelaire, or Whistle and are typically used for surgical procedures. SILASTIC Brand Catheters are smooth, non-stick silicone exterior coating reduces calcification build-up. Firm, but flexible, latex-based construction with large drainage lumen. (336xx & 334xx ).