Honeywell Aquastat Controller, Circulator Control and High Limit or Low Limit, Immersion Device for Limiting or Regulating Temperature of Liquids, 3/8″ x 2 7/8″ Copper Bulb, SPDT Contacts, Horizontal or Vertical Mounting, 100-240 Degree Operating Temperature Range, 3″ Capillary Length, 5-30 Degree Fixed Differential Temperature