The material of the cover will affect your pickup tone. Nickel silver will cause a subtle decrease in treble response, brass will cause a far more significant decrease, Brass is perfect for taming bright pickups.
Slide on top of your humbucker and solder each side onto the baseplate. The plating may require some scratching/filing for a strong solder joint.
Please note our black is more of a black chrome colour, rather than a jet black colour.
See our printable PDF to check for size - https://drive.google.com/open?id=1JgWsIb895CHTMkQF2cagFZoJCgchpxUB (50mm)