Use the following chart to aid you in selecting the right Galvanic Timed Release for you:
EXAMPLE: Water is 60F (16C) and you want a 3 Day release. Follow the 60F (16C) line down until it reaches the 3 Day line, your size is C4.
USD Ultra Short Duration Release, battery powered for durations in minutes
HL500 High Load Galvanic Release, capable of handling static loads up to 500 pounds for release times as required
HL1000 High Load Galvanic Release, capable of handling static loads up to 1000 pounds for release times as required.