[CygnusX1]

Do any of you lads know why some DMZ pups use the traditional slotted screws & slugs, while
others use allen screws all around?

[greenlion]

Different sizes and types of screws create different tones.

[CygnusX1]

Thank you! 

[idsnowdog]

Each type of pole has different tonal variations and they are used to tune the response of each type of pickup.  My theory is that since Dimarzios mostly use brass baseplates which accentuate the midrange that's why they use mostly hex heads because they attenuate the midrange and sharpen treble response.