HVAC Field Service Tool:Dual Size 1/4 & 5/16 Schrader/Schroeder/Dill Valve Core Remover/ Installer/Changer R22 R410a Refrigeration Air Condition Services HVAC Air Contitioning tool for removing and installing damaged valve cores in charged systems; Dual size to work on charge systems of R410a or R22 or other retrofit replacements systems; Easy to use, save hours of avacuation and charging time; same function as Robinair 18560 or Mastercool 91496, but 2 sizes Ports: 1/4 and 5/16 flair Ports Professional Service tool, thousands we sold are i the hands serving