These can be easily fixed there are tons of replacement parts on eBay! For very cheap prices! Plus nice carrying case! They did test working a couple of years ago . I assume they still work.
eBay
Model:For Sony WH-CH710N/ WH-CH700N /WH-CH720N Headphones. Large capacity, can fit your Sony WH-CH720N / WH-CH710N / WH-CH710N Wireless Noise Canceling Subwoofer Headphones Noise Canceling Wireless Headphones Bluetooth Headphones perfectly with a recess for storing cables or charging cables.
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Tecnologia: Li-Poly Capacità: 550 mAh Tensione: 3,85 V Energia: 2,12 Wh Dimensioni (L x l x A): 2,7 x 2,5 x 0,7 cm Numero di celle: 1 Peso: 8 g Lunghezza cavo: 2,4 cm Compatibile con i seguenti modelli: Sony INZONE H9 Sony WH-CH720N Sony WF1000XM4 CHARGING CASE Per garantire la compatibilità, verificare se la batteria ricaricabile attualmente in uso è presente nell'elenco. Compatibile con: Sony FT702028P Sony 722428 .
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Kopfhörer Schutz Aufbewahrungstasche Anti Kratzer Kopfhörer Aufbewahrungstasche Stoßfestes Staubdichtes Zubehör für SONY WH-CH720N/WH-CH520. Kompatibilität: Geeignet für Sony WH-CH720N/WH-CH520/für XBOX Kopfhörer/für Apple-Max/für Trailer EDIFIER W820NB (EDIFIER Free Pro) und andere Kopfhörer.
eBay
Applicable Models: for WH-CH710N CH720N. Made of high quality faux leather and Sponge material, designed for comfort and style. Material: Synthetic leather + Sponge. Comfortably fits your ear, soft and smooth, comfortable to wear.
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Materiale: silicone. Per Sony WH-CH720N. Peso: 19,4 grammi.
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Equipped with high-performance microphones and multiple features, these headphones are ideal for music lovers, remote workers, and frequent travelers seeking premium sound quality and convenience. - Type: Wireless Noise Cancelling Headphones.
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Compatible with Sony WH-1000XM6 / WH-1000XM5 / WH-1000XM4 / WH-1000XM3 / WH-XB910N / WH-CH720N / ULT WEAR WH-ULT900N / INZONE H5 / Bravia Theatre U HT-AN7 / WH-1000XM2. New and unused. Price is for one cable.
eBay