This is a 6 ohm speaker and can only be used with the ESU LokSound Range of DecodersAn 8 ohm version is available CLICK HERE NEW to the DCCS range of High Performance Dynamic Speakers for Model Locomotives.Our range of speakers are designed to fit inside locomotives with limited space where other speakers simply won't fit and yet provide superior sound performance like no other on the market.The DCCS - "MICRO-6" is a super compact rectangular speaker, that features an intergated sound enclosure making its overall size of 15mm x 11.5mm x 4mm high. This speaker produces incredibly huge sound across a large frequency range. Featuring 6 ohm Impedance this speaker is only suitable for use with ESU LokSound Decoders making it a perfect partner for our Custom Sound Projects featured on the ESU LokSound V4.0 Decoders available from DCC Solutions.The reason this speaker produces incredible sound quality compared to other speakers on the market of this size is by providing a whooping 81cubic mm Air Pumping Capacity. The more air a speaker can move, the louder the speaker can get; In a nutshell.For the size of this speaker, it wil impress you!DCCS "MICRO-6' Speaker Specifications:Total Height with Enclosure - 4 mm " That's INCREDIBLE" Total Size with Enclosure - 15mm x 11.5mmImpedance of 6 OhmsUnique Silicone cone providing highest robustness performanceNominal Power Rating - 0.7 WattMax Power Rating - 1 WattFrequency Range - 300Hz~20kHzSound Pressure Level - 74dbMax. Sound Pressure Level - 94dbAir Pumping Capacity - 81mm³