This is the best cheapest option for putting Gas or OIl , Dye and testing the Low pressure side of a car air conditioner system on Cars or Trucks . Note all Airconditioning repairs And servicing need  suitably qualified people to do  these job and wearing Safety glasses and gloves as the Gas does cause burns to human part . This gas does not mix with R134A so needs to be put in and empty system and really needs the oil changed as well