The P90 pickup was designed by Gibson way back in 1946. There are 3 different types of these pickups – The P90 with a humbucker type casing is slightly smaller than a standard humbucker in width but bigger than a single coil. The P90 dog ear has extensions on either side of the pickup which resembles dog ears. The last version is the P90 soap bar which is shown below. This version, as I’m sure you can guess gets its name due to its obvious resemblance to a bar of soap. P90’s are actually single coil pickups but use bar magnets in the same way as humbuckers as opposed to the pole magnets found in single coils. This results in a pickup that sounds like a single coil in some aspects but also has sounds associated with a humbucker due to the similar magnet layout.