H4

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

Science and mathematics

• 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
• Hydrogen-4 (H-4), an isotope of hydrogen
• H4, a symmetry group in the fifth dimension; see H₄ polytope
• H-4, a huge eruption of the Hekla volcano around 2310 BC

Technology

• H-4 SOW, a precision-guided glide bomb used by the Pakistan Air Force
• H4 (chronometer), an 18th-century marine chronometer designed by John Harrison
• Zoom H4 Handy Recorder, a handheld digital audio recorder
• , level 4 heading markup for HTML Web pages, see HTML element#heading

Transport

Automobiles and roads

• H4, a halogen headlamp bulb
• H4, development name of the Hummer HX concept car
• H-4, shorthand for a 4-cylinder horizontally opposed or "flat four" engine
• H4 Dansteed Way, a road in Milton Keynes, England

Aviation

• GEN H-4, a Japanese helicopter design
• Hughes H-4 Hercules (Spruce Goose), the largest flying boat ever built
• Héli Sécurité Helicopter Airlines (IATA code), based in France; see List of airline codes (H)
• Inter Islands Airlines (IATA code), a former airline 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

Rail

• GNR Class H4, a class of British steam locomotives

Other uses

• Halo 4, a video game created by 343 Industries for the Xbox 360
• H4 (film), a 2013 film
• 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
• H4 (classification), a cycling classification used in para-cycling

See also

• 4H (disambiguation)
• HHhH, a novel by the French author Laurent Binet