part number L300-40.
300 Degree 2 Wire Thermostat.
Opens at 300, Closes at 260 Degrees Fahrenheit.

The L Series of 3/4" (19mm) bimetal disc temperature controls offers proven reliability in a versatile, cost-effective design. Can handle loads up to 25 amps at 240VAC.

Features:
Close when temperature differential is reached
Open on rise
1/4" quick disconnect terminals
Welded construction for integrity of current-carrying components
60T electrical ratings
WARNING: Prop 65 info