Overview: Output Power:2WRMSSNR gt;=60d BAFM Sensitivity:75ΩUSB Input Power:5V/500m A Speaker:Φ31MM 2W 4Ω Frequency Response:20-20KHZ, ±3d BTF Card Reader MP3 Player amp; Card Reader Speaker MP3 Player Supports MP3 Audio Format Support TF Card Up To 8GB (Not Included) Built-In Lithium Battery (can play 3~5 hours for fully charged) Just Use One TF Card For Both The MP3 Player & Speaker Carry The MP3 Player When You Are Out & Export The Music To The Speaker When At Home Specification: Weight Approx:105.7g Size Approx:10 x 4.5 x 4.5