H4

H4, H04, or H-4 may refer to:

Biology and medicine

• ATC code H04 Pancreatic hormones, a subgroup of the Anatomical Therapeutic Chemical Classification System
• Histamine H₄ receptor, a human gene
• Histone H4, a protein involved in the structure of chromatin in eukaryotic cells

Technology

• H-4 SOW, a precision-guided glide bomb used by the Pakistan Air Force
• Harrison Number Four, an 18th century marine chronometer designed by John Harrison
• Zoom H4 Handy Recorder, a handheld digital audio recorder

Transport

Automobiles and roads

• H4, a halogen headlamp bulb
• H4, development name of the Hummer HX concept car
• H-4, a Subaru flat-four engine
• H4 Dansteed Way, a road in Milton Keynes, England

Aviation

• Hughes H-4 Hercules (Spruce Goose), the largest flying boat ever built
• H4, IATA code for Héli Sécurité Helicopter Airlines, based in France
• H4, IATA code for Inter Islands Airlines, based in Cape Verde

Ships and submarines

• HMS H4, a 1915 British Royal Navy H class submarine
• HMS Tenedos (H04), a 1918 British Royal Navy Admiralty 'S' class destroyer
• USS H-4 (SS-147), a 1918 United States Navy submarine

Trains

• GNR Class H4, a 1920 British 2-6-0 steam locomotive model

Other uses

• H-4 visa, issued by the U.S. Citizenship and Immigration Services
• British NVC community H4, a heath community in the British National Vegetation Classification system

See also

• 4H (disambiguation)