The SMAN2 and SMAN3 are like no other digital manifolds on the market - they"re the only manifolds that automatically calculate target superheat, so you don"t have to worry about guesswork or manual calculations. Plus they"re the only manifolds with the ability to perform a linear adjustment of the pressure sensors based on refrigerant type, temperature, and pressure, and it"s so easy, you can do it right in the field. WIth the SMAN3 you also get a built-in micron gauge with resolution from 50 to 9,999. On top of that, the SMAN3"s exclusive micron alarm allows you to set the alarm to a chosen micron level, and when the vacuum reaches that level, the alarm will sound, freeing you up to keep working when pulling a vacuum.