Easy, snap together assembly. UL listed to Marine Combustible Gas Indicators UL 1110. Power 12 vDC, operational range 7-16 volts. 200 milliamp (.2 amp.) current draw. Alarm Trigger: 20% or less of the lower explosive limit of gasoline. Fumes Detected: Gasoline, hydrogen from batteries, propane, alcohol, acetone, methane and other explosive vapors. On/Off/Test Switch. For one touch analysis of detector performance. Size: SA-1 fits standard 2-1/8" in dash panel blank. SA-1XL: 3-1/4"W x 2-3/4"H x 3/4"D.