Under the HQ element are two to four SEAL platoons of 16 men (two officers and 14 enlisted SEALs, and sometimes assigned non-NSW support personnel); a company-sized combat service support (CSS) and/or combat support (CS) consisting of staff N-codes (the Army and Marine Corps use S-codes); N1 Administrative support, N2 Intelligence, N3 Operations, N4 Logistics, N5 Plans and Targeting, N6 Communications, N7 Training, and N8 Air/Medical. Each 16-man platoon can be task organized for operational purposes into two eight-man squads, four four-man fire teams, or eight two-man sniper/reconnaissance teams. The size of each SEAL "Team", or "squadron", with two to four task units (containing a total of eight platoons) and support staff is approximately 300 personnel. The typical SEAL platoon has an OIC (officer in charge), usually a lieutenant (O-3), a platoon chief (E-7/E-8), and two squads commanded by a LTJG (O-2) and a squad leader (E-6). The remaining members of the squad are operators (E-4 to E-6) with their specialty skills in ordnance, communications, diving, and medical. The core leadership in the troop and platoon are the commander/OIC and the senior enlisted NCO (Senior Chief/chief). Platoon core skills consist of: Sniper, Breacher, Communicator, Maritime/Engineering, Close Air Support, Corpsman, Point-man/Navigator, Primary Driver/Navigator (Rural/Urban/Protective Security), Heavy Weapons Operator, Sensitive Site Exploitation, Air Operations Master, Lead Climber, Lead Diver/Navigator, Interrogator, Explosive Ordnance Disposal, Technical Surveillance, and Advanced Special Operations. Naval Amphibious Base Little Creek, a naval base in Virginia Beach, Virginia, is home to SEAL Teams 2, 4, 8, 10, and 18. Naval Amphibious Base Coronado, a naval base in Coronado, California, is home to SEAL Teams 1, 3, 5, 7, and 17. There are also two SEAL Delivery Vehicle (SDV) units, SDVT-1 and SDVT-2, located in Pearl Harbor, Hawaii and Little Creek, Virginia, respectively. SDV Teams are SEAL teams with an added underwater delivery capability. An SDV platoon consists of 12–15 SEALs. Special warfare ratings The Special Warfare Operator rating (SO) and Special Warfare Boat Operator rating (SB), were established in 2006. Special Warfare Operators (SEALs) and Special Warfare Boat Operators (SWCCs) are no longer required to maintain the original rating they qualified in upon joining the Navy. The following ratings are specific to Navy SEALs: United States Navy Parachute Team "Leap Frogs" The primary mission of the Navy Parachute Team (NPT) is to support Naval Special Warfare recruiting by gaining access and exposure to appropriate candidates through aerial parachuting demonstrations.