AO Smith L4006A1967 Aquastat, breaks on rise, 100-240F range, 240F factory stop, 5-30F adjustable differential

 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 Differential Range, 1/2" Well Spud Size

is identical to /U