Features: 1. Made of stainless steel material, durable, sturdy and rust-resistant. 2. 4 in 1 straightedge spans nearly three frets, which enable it to check any fretted instrument and indicate uneven fret heights, very convenient. 3. Suitable for electric guitar, electric bass, wooden guitar, folk guitar, electric box guitar etc. 4. Accurate straight edges can help your to detect any discrepancy existing in frets height.