High Capacity: No longer to worry about the endurance of the batteries, Kastar high capacity battery will provide ultra strong power for your headphone to performance well and operate longer. Battery Specification: Battery Type: Ni-MH; Battery Voltage: 2.4V; Battery Capacity: 1000mAh; Battery Dimensions: 1.8" x 0.9" x 0.45" (46.00 x 23.00 x 11.3mm). Safety Assurance: Kastar add mix-protection additive to the cathode of batteries, protect the material from degradation in the progress of charge and discharge, extend lifespan up to 1200 cycles. Low self-discharge: Embedded seal structure expand the space of crystal lattice, make more room for hydrogen, so Kastar batteries will holds power longer than others. Environmental Protection: Ni-MH eco-friendly cell, doesn't contain Hg/Cd/Pb, makes no pollution to the environment, and using DBCK steel shell which can protect the battery against explosion due to overpressure. Warm Reminder: Can use "Ctrl" + "F" easily to find your models

1. Compatible with the following Sony battery models:

Sony BP-HP550-1 BPHP5501
Sony BP-HP550-11 BPHP55011
Sony BP-HP800-11

2. Compatible with the following Sony headphone models:

Sony MDR-IF245RK MDRIF245RK
Sony MDR-RF4000 MDRRF4000
Sony MDR-RF4000K MDRRF4000K
Sony MDR-RF4000RK MDRRF4000RK
Sony MDR-RF4000-1 MDRRF40001
Sony MDR-RF810 MDRRF810
Sony MDR-RF810RK MDRRF810RK
Sony MDR-RF840 MDRRF840
Sony MDR-RF840RK MDRRF840RK
Sony MDR-RF840RJ MDRRF840RJ
Sony MDR-RF850 MDRRF850
Sony MDR-RF850RK MDRRF850RK
Sony MDR-RF860 MDRRF860
Sony MDR-RF860RK MDRRF860RK
Sony MDR-RF925 MDRRF925
Sony MDR-RF925RK MDRRF925RK
Sony MDR-RF970 MDRRF970
Sony MDR-RF970RK MDRRF970RK
Sony MDR-RF995 MDR-RF995RK
Note: NOT compatible with Sony WH-RF400 Wireless Headset