" Made of high quality brass alloy, the adapter fitting has a strong seal for durability and safety. The coupler nuts are deeply knurled for quick hand tightening. This swivel straight connector has a thimble, during the operation, it will not open the central air conditioning tube, completely solve the fluoride leakage injury problem, safety is guaranteed. The mini split adapter fitting can be used on most new R410A ductless mini split systems.Perfectly suitable for air conditioners, HVAC and refrigeration systems of the R410a split split system. 1/4" SAE male adapter to 5/16" SAE female quick connects converts 1/4" SAE (new style R410a) charging vacuum ports to accept a set of 5 gauge SAE hoses /16"". We strive to provide you with quality and convenient service. You are welcome to contact us if you have any problem with our product, we will give you a satisfactory answer. "