This replacement elbow and swivel is for your Zest Nasal CPAP mask only. Helps your tubing rotate freely to eliminate any tugging.
The original Zest has the exhalation vent holes molded right into the frame above the elbow. So this Zest Elbow Assembly does not have any exhalation vent holes.
This is different than the Zest Q Elbow Assembly SKU 400HC227 that includes the Diffuser exhalation vent. The elbows are not interchangeable.