RC-681M Replacement Remote for Onkyo HT-R508 HT-R550 AV ReceiversRC 681M Replacement Remote for Onkyo HT R508 HT R550 AV Receivers. No programming required, plug and play. 2x AA batteries are required (not included). Compatible with (but not limited to these models): RC681M HT CP807 HT R508 HT R550 HT R550S HT R557 HT SP904 HT SP908 HT SR750 HT SR750S HT SR800 HT SR800B HT SR800S TX SR505 TX SR505S TX SR575 TX SR575S