Danish Model 1854 Socket Bayonet with Kyhl's Locking Spring. Bayonet measures 22.50" overall with a socket length of 2.75", 19.5" blade and inside socket diameter of .850".  Top of Socket is numbered/Unit Marked, elbow appears to have some cartouches. Metal has a brown age patina, rust. See photos for further details, clarification, and condition.