Stagg KG475CR Chrome-Plated Bass Guitar Machine Heads

These aren't the highest quality, but how much do you want to spend? If you're fixing up a cheap-ish bass, these'll do the job. I've just fitted a set to a Stagg electric double bass, and the bassist says they're much better than the ones the distributor retro-fitted before he bought it. This is a four-in-line set, but you can dismantle them and turn the worm gear to reverse them, so you have two-a-side; this does change the tuning key direction, but on the plus side, the double bass now works! Quality seems ok so far, no nasty burrs or sharp edges, and they turn smoothly enough and hold tune. Job done!