AO Smith L4006A1967 ?Aquastat Controller, High or Low Limit, Immersion Device for Limiting or Regulating Temperature of Liquids, 3/8" x 2 7/8" Copper Bulb, SPST Contacts Break on Temperature Rise, Horizontal or Vertical Mounting, 100-240 Degree Temperature Range, 1 1/2" Capillary Length, 5-30 Degree Adjustable Differen