Tenor drums are used as a marching percussion instrument, commonly as mounted sets of 4-6 drums allowing one person to carry and play multiple drums simultaneously. Other names for these drums include names specific to configurations by number of drums: "duos" (2 drums), "tris", "trios", "trips", or "triples" (3 drums), "quads" (4 drums), "quints" (5 drums), and "squints," "hexes," "six-packs," "tenors" or "sextets" (6 drums). The number-specific term "quads" is often used as a generic term for configurations with more than four drums due to it being the original and most common configuration.

Typically there are four main drums, usually either 8, 10, 12, and 13 inches in diameter (which is referred to as a high school configuration or small block tenors) or 10, 12, 13, and 14 inches in diameter (referred to as a Corps configuration or big block tenors), plus one or two accent drums (typically 6 or 8 inches in diameter). The accent drums are also known as shot, gock, spock, or spike drums; they are usually tightened as high as they can go to achieve maximum effect. Other percussion instruments, such as cowbells or cymbals mounted to the rim, are sometimes also added.

Source: Wikipedia