The unique appearance of the pickups comes from part of the process which creates them - the units are resin cast, eliminating the need for any form of cover. The humbuckers are built in a rubber mold into which the magnets and coils are inserted, a special grade of resin is then pored over the entire thing, resulting in a perfectly sealed and shielded pickup.
All my current guitars are fitted with a very rare 'new old stock' Russian military 0.022uF paper in oil K40Y-90 capacitor ! Why ? Because I do not cut any corners, it makes no difference at all to fit a cheap cap but why would I do that after spending 100 hours building the guitar ? I want every part to reflect my passion and dedication to my craft and this also applies to the parts which are not directly visible.