Intermatic T104P201 Installation manual

Model T104P201 with Plastic enclosure
Model T104R201 with Metal enclosure
24 Hour Dial Time switch with Fireman switch
240Volt timer with heater protection that turns off
gas-fired pool heater 15-20 minutes before turning off
filter pump. This eliminates knocking due to overheated
water, reduces scale and lime, and extends service life of
heater
Heater protection circuit: 10A 240V max.
WG1573 clock motor/ 156T1978A Tripper / 9-3/8” H x 5-1/2” W x 3-5/8” D/ ½” and ¾” KO on back and side

Typical wiring for timer
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html
http://waterheatertimer.org/Intermatic-timers-and-manuals.html#pool