Robertson Worldwide warrants to the purchaser that this ballast will be free from defects in material or workmanship for a period of 2 years from date of manufacture when properly installed and under normal conditions of use
http://www.amazon.com/Robertson-50130-BLU0050A05100-Pressure-Ballast/dp/B000UX5XD6/ref=sr_1_203?ie=UTF8&qid=1375916834&sr=8-203&keywords=robertson+ballast ; http://www.robertsonww.com/products/spec_sheets/BLU0050A05100.PDF