A mono wig uses a monofilament mesh area where hair is individually tied so the part or crown looks like scalp.
Mono top
A mono top gives the most parting flexibility. You can often change the part direction more naturally.
Mono part or crown
A mono part is smaller and more affordable. A mono crown creates realism at the crown but less parting freedom.
Bottom line
Choose mono construction when scalp realism and comfort matter more than the lowest price.