Mint never hinged

Mint Never Hinged
Mint Never Hinged refers to the gum on stamps that have gum without a fingerprint, blemish or mark of any kind. This is the preferred condition in which to save Mint PNCs.
Miscut ...

These stamps are Mint Never Hinged (MNH). A mount is used to protect the stamp in this case. Mounts are costly and beginners who collect stamps off envelopes need not go in for this.

The highest grade is unmounted mint or mint never hinged. The term mint never hinged has developed to provide reassurance to buyers that the stamp has not been tampered with to remove traces of mounting, ...

For mint never hinged (MNH) stamps, in most cases expect to bid 60-80% or even above the 100% mark. Since you're not competing against "floor bidders," winning bids are accepted at the discretion of the mail bid organizer.

See also: Stamp, Used, Never hinged, Gum, Hinged