Here's a revised version of your text to avoid duplicate semantics:
[NOTE] You may observe that the central plastic component differs from the original equipment manufacturer (OEM) part. While this may cause some initial doubt, I urge you to test it – you will find that it fits smoothly and functions without any issues.
[USEFUL LIFE] For peak efficiency of your filtration system, it is recommended to remove approximately 4 gallons of water before the initial usage. Enjoy fresh by replacing every 6 months or 200 gallons, whichever comes first.
[EASY REPLACEMENT] Easy for installation and operation, without water leakage and connection issues.
[NSF CERTIFICATION] Certified and tested to NSF/ANSI 42 standard to reduce chlorine, odor and retain beneficial minerals in your water.