Mark XVIII explained

Mark XVIII or Mark 18 often refers to the 18th version of a product, frequently military hardware. "Mark", meaning "model" or "variant", can be abbreviated "Mk."

Mark XVIII or Mark 18 may refer to:

Technology

a Royal Air Force night fighter radar modification
a further development of the Mk XIV, arriving too late to serve in World War II
1953 American nuclear bomb
former US Navy grenade launcher

Other uses