This high quality compact speaker features a rechargeable Lithium-Ion battery &8211; charges from computer USB (Universal Serial Bus) port. Extension cable &8211; for flexible placement of speaker while using the Sky Scout. Nylon Lanyard &8211; to hang the speaker around your neck while using the Sky Scout. Expandable woofer &8211; for optimum sound quality The speakers have been thoroughly tested & guaranteed not to affect the Sky Scout pointing accuracy.