The רב-סמל ראשון rav samal rishon (abbreviated: "rasar") (master sergeant) is a non-commissioned officer (נגדים) rank in the Israel Defense Forces (IDF). Because the IDF is an integrated force, they have a unique rank structure. IDF ranks are the same in all services (army, navy and air force). The ranks are derived from those of the paramilitary Haganah developed in the British Mandate of Palestine period to protect the Yishuv. This origin is reflected in the slightly-compacted IDF rank structure.
The eighth enlisted rank in the U.S. Army, just above sergeant first class, below sergeant major, command sergeant major, Sergeant Major of the Army and equal in grade but not authority to first sergeant. It is abbreviated as MSG and indicated by three chevrons above three arcs. A master sergeant is typically assigned as a brigade-level section noncommissioned officer in charge and serves as the subject matter expert in his or her field, but may also hold other positions depending on the type of unit. The equivalent-grade first sergeant is the senior noncommissioned officer of a company-, battery- or troop-sized unit. The rank of master sergeant is usually held by staff members serving as NCOICs as well as commonly held by the motor pool NCOIC as the advisor to the motor pool chief, who is usually a warrant officer. When holding the position of first sergeant, while uncommon, the master sergeant is referred to as "first sergeant", however; when not in the position of first sergeant, master sergeants are addressed as "sergeant". This is the standard address for all pay grades E-5 through E-8. Use of the term "top" or "master sergeant" is not a requirement, but is considered courteous and remains to be at the discretion of the one addressing the master sergeant.
The eighth enlisted rank in the U.S. Marine Corps, just above gunnery sergeant, below master gunnery sergeant, sergeant major, and Sergeant Major of the Marine Corps. It is equal in grade to first sergeant. It is abbreviated as MSgt. In the U.S. Marine Corps, master sergeants provide technical leadership as occupational specialists at the E-8 level. Most infantry master sergeants serve as the operations chief of a weapons company, in place of the gunnery sergeant found in the company headquarters of a rifle company. Infantry master sergeants also serve as the assistant operations chief in the S-3 section of the headquarters of an infantry regiment and Marine Expeditionary Unit and in the G-3 section of the headquarters of a Marine Expeditionary Brigade. The Marine division and Marine Expeditionary Force headquarters contains two infantry master sergeants, one as the training NCO and the other as the readiness chief. While some combat support battalions have master sergeants at the company level (e.g., one as the tank leader, again replacing the company gunnery sergeant, in the operations section of the tank company headquarters, and two in the company headquarters of an assault amphibian company, one master sergeant as the company gunnery sergeant in the headquarters section and the other as the section leader of the company headquarters AMTRAC Section), most non-infantry master sergeants serve as section chief/NCOIC of their MOS type staff section in a battalion or higher level headquarters. General command leadership at this paygrade is provided by the separate rank of first sergeant. Only in the Marine Corps are master sergeants required to be addressed as "master sergeant". In the Marine Corps, master sergeants may be referred to by the nickname of "Top". This usage is an informal one, however, and would not be used in an official or formal setting. Use of this nickname by Marines of subordinate rank is at the rank holder's discretion. In the U.S. Armed Forces, all master sergeants (Army, Air Force, and Marine Corps) are senior non-commissioned officers (i.e., pay grades E-7 through E-9). However, in the U.S. Marine Corps, the non-commissioned officer ranks of staff sergeant and above, are classified as Staff Non-Commissioned Officers (SNCOs), a classification that is unique in U.S. usage to the USMC.
The seventh enlisted rank in the U.S. Air Force, just above technical sergeant and below senior master sergeant. It is abbreviated as MSgt. Advancement to master sergeant is one of the most significant promotions within the enlisted Air Force. At the rank of master sergeant, the airman enters the senior non-commissioned tier and his or her duties begin to focus on leadership and management rather than technical performance. Per Air Force Instruction 36-2618, master sergeants typically serve as flight chiefs (analogous to platoon sergeants in the U.S. Army) and section chiefs (leaders of duty sections within a squadron). It is also the lowest rank in the Air Force that one can hold in order to attain the special duty position of first sergeant. These Air Force first sergeants occupy the pay grades of E-7 through E-9 and are referred to officially as "first sergeant" regardless of their pay grade, and unofficially as "first shirt" or simply "the shirt". In 1991 the Air Force changed its NCO insignia so that a maximum of five stripes, or rockers, were placed on the bottom of the chevrons. The master sergeant rank insignia was changed by removing the bottom (sixth) rocker, and relocating it above as a single chevron, on top of the five lower stripes.