The M-Series design is intended for Right-handed operation, a Left-handed version is available! So please purchase the version best suited to your preference.
In some situations a user can assist the Right-hand with additional left-handed grip to operate the bolt action, but the bolt-lever of a Right-handed UPK-M1 should always be manipulated with the right-thumb. IF a situation arises (greasy hands, blood, and other liquids) and using a knife with slippery hands is unavoidable. It is suggested to assist the right-handed method with the left hand, by using the left-thumb and two forefingers to add grip at the top end of the handle with the right hand still around the base of the handle, while continuing to operate the bolt-lever with the right-thumb.
CAUTION!!! DO NOT manipulate the bolt-lever of a Right-handed UPK-M1 knife with the left hand, while holding the handle with the right hand. If not familiar with the bolt-lever motion, during deployment the bolt-lever engagement into a deployment slot will partially recess the bolt-lever into a slot, this reduced purchase could allow the left hand to slip toward the now deployed and locked open blade. The blade is very SHARP! and this combination has been observed to have bad results, so don't operate a Right-handed UPK-M1 bolt-lever with a left-hand.