A kirby grip or hair grip is a type of small double-pronged hairpin or clip invented by Luis Marcus and used to to hold hair in place like up-dos, buns, and other hair styles where a sleek look is desired.
A bobby pin (also known as a kirby grip or hair grip in the United Kingdom) is a type of hairpin, usually of metal or plastic, used in coiffure to hold hair in place. It is a small double-pronged hair pin or clip that slides into hair with the prongs open and then the flexible prongs close over the hair to hold it in place. The bobby pin was invented by Luis Marcus, a San Franciscobased cosmetics manufacturer, after World War I and came into wide use as the hairstyle known as the "bob cut" or "bobbed hair" took hold. In addition to bobbed hair, bobby pins are often used in up-dos, buns, and other hair styles where a sleek look is desired. 
