The Mini SpiderCapo was produced to fit narrow necked instruments such as the banjo, ukulele, mandolin and bouzouki. However, it's capable of working worth any stringed instrument that meets the necessary qualifications. For example, users of the Mini SpiderCapo have reported that because it clamps over the fingerboard, and not behind, it can also be used on a Mountain Dulcimer. Achieve hundreds of different tunings without de-tuning your instrument by Capo-ing each string with the Mini SpiderCapo. Banjo players tend to make a habit of tuning in different ways to start with, and SpiderCapo will multiply each tuning by the same amount making a seemingly unlimited amount of tunings available. Works best on fingerboard widths between 29-51 mm or 1.125-2 inches.