H4

H4 or H-4 can mean:

• For the engine configuration, see flat-4
• A dual-filament headlight bulb for automobiles
• Harrison Number Four, an 18th century chronometer designed by John Harrison
• Histone H4, a component of DNA higher structure in eukaryotic cells
• The proposed SUV Hummer H4
• H-4 visa commonly known as H4 visa, status granted to the immediate family members (spouse and children under 21) of the H-1B visa holders
• The Hughes H-4 Hercules (Spruce Goose) aircraft
• Héli Sécurité Helicopter Airlines and Inter Islands Airlines IATA airline designators
• British NVC community H4, Ulex gallii - Agrostis curtisii heath