I just got the Grover 406C6 Mini Locking Rotomatic guitar machine heads, and they are awesome! These tuners have 18:1 gearing for micro-tuning, cast housings with sealed lubrication, and adjustable-tension metal mini knobs. These tuners are great, I much prefer them over anything else I've tried. The auto locking feature makes changing strings VERY easy, you just pull the string taught, and tune to pitch. They are very smooth and responsive when turning the knobs, and they can really help when tuning in strange steps (1/4 step down, up, etc...) Overall I'm highly satisfied with the tuners, and at $55, they were a bargain.