The package says “For optimal performance, the Pojie should be replaced with each stringing,” yet this set of Pojies has just been strung for the 4th time. The racquet belongs to a tennis pro who is on court teaching, hitting, or playing 30+ hours a week. The polyurethane compression cores in contact with the strings have become slightly deformed, but appear to have some life in them yet. The black string guides look to be in good condition.
He will probably need to replace his Pojies at his next re-stringing, particularly since one of his primary reasons for using Pojie is to reduce the effect that hitting so many tennis balls has on his elbow. As the Pojie loses it's elasticity, it's ability to absorb impact is also diminished.
For more information, see our post “How often should I replace my Pojie?”