Anderson-Bolds Stocks Fenwal 17000-0 series Temperature switches.
The Fenwal THERMOSWITCH developed by Dr. Wall and Mr. Fenn in the 1930's is still used to day for accurate Temperature control for commercial and industrial applications. The THERMOSWITCH used the method of dis-similar metals to measure temperature. The outer shell and interior struts expand and contract at different rates and by use of a spring the switch can be adjusted to require more or less expansion for different temperature settings.
The Fenwal Series 17000-0 is a simple cartridge style thermostat, 5/8 inch in diameter and 3.72 inches long.
It is made of brass or stainless steel, the brass version has a range of -100 to 400F and the Stainless Steel has a range of -100 to 600F.
The Fenwal 17000-0 series also has the following versions:
Fenwal HEX Head style with a Hex nut and 1/2 inch NPT pipe thread mounting. 17100-0
The Fenwal Block Head style for adding certain Modifications. 17200-0
The Flange Mount with Block head for easy mounting. 17300-0
The Fenwal 17800-0 with terminal box, NPT threads and knob and dial.
The Fenwal 18000-0 series with double headed fittings (coupling head).
All the above versions come in a stainless steel versions as well as open-on-temperature rise or close-on-temperature rise versions.