The Bare Knuckle Pickups Brute Force Bridge Humbucker is hand wound in the UK, features ceramic magnets and is mainly aimed at progressive metal, thrash, hardcore and extreme metal styles. From their Boot Camp range, the Brute Force pickups are in the high output range and produce a deep, saturated tone. The Bare Knuckle Boot Camp is a stripped back, no-nonsense pickup range aimed at guitar players who just want to cut to the chase and have great tone. The 50 mm pole spacing is the standard for guitars with fixed bridges (e.g. Gibson Les Paul), the 53 mm spaced humbuckers (also called F-spaced or trembuckers) are used on guitars with tremolos.