The non-instrumental Christian church doesn't believe you should use any form of musical instrument not named in the New Testament ~ which is why they sing a'capella.
Every time this question is brought up we find various Freepers who do or do not include the non-instrumental congregations in the Restoration circle.
Good reference ~ someone with some knowledge of the Restoration belief made sure to show the connection (via dotted line) back to the time of the Christian congregation in Jerusalem.
Was at a funeral last month, in one of the yellow counties on that map. Turned out to be a Church of Christ. The dedication stone said "Founded by Jesus Christ in AD 33". It was all very happy-clappy evangelical, except for one passing comment by the presiding minister that, if you were paying attention, pointed to their belief in necessity of baptism for salvation. It didn't seem the time or place to raise a ruckus about it.
I'm not sure how useful the map is. According to it, we should be tripping over Roman Catholics here. They are there, but so's most everybody else. Driving down the street, you're far more likely to see a mainline Protestant church or one of these generic non- (or weakly) denominational evangelical churches.