Delta Controls Pressure Differential Switch ¼. Material Stainless Steel / PTFE / Viton. New, unused, ex stores stock. Missing original packaging & paperwork.One of the countries largest stockists of new and used surplus equipment. Over 20 years experience in dealing with Pharmaceutical, Process, Chemical & Automation Equipment. If possible, the goods will be exchanged with a duplicate item from our stock. These are not included in the item list price.