When selecting nozzle holders, you must prioritize material compatibility and pressure ratings. For high-pressure applications like pressure washers or CNC coolant systems, ensure the holder is made of 304/316 stainless steel or heavy-duty brass to prevent corrosion and thread stripping. Verify the thread type (NPT, BSPP, or Metric) to ensure seamless integration with existing spray wands or manifolds. Additionally, check the maximum operating temperature if the holder will be used in hot water or steam cleaning environments.