Seymour Duncan SL59-1N WH

This gives a humbucker sound in a single coil size.
It's quite an easy fit to a stratocaster or similiar guitar where you don't want to change the original pickguard or rout the body of the guitar.
It's got a nice fat mid rangey sound.
The adjustable pole piece are very handy whether you have a flat neck or a curved fingerboard.
It's a bit louder than a standard single coil but not massively so, it's easy to get a good balanced sound out of this pickup and the standard pickups I had on my stratocaster.
The 4 conductor cable is handy if you want to be able to wire up single coil configurations as well as humbucking selections