Designed for acoustic guitars, the 3AV magnetic pickup mounts in the soundhole. It has a bright, clear hum-canceller (stacked coil) with B-string compensation*. It includes the plastic mounting brackets and a 10 foot cable with strain relief. The brackets make it easy to install the pickup to your guitar for gigs at the coffee shop or stage and then remove when playing solo.The adjustable brackets fit most soundholes from 3 7/8 inches diameter and larger.