The typical Elizabethan consort of viols was composed of six instruments: two basses, two tenors and two trebles, or one bass, three tenors and two trebles (see Chest of viols ). Source: Internet
The bridge is made so that it tapers in height and length, with the small end holding the trebles and the higher and wider end carrying the basses. Source: Internet
There are also other bets which are large combinations of singles, doubles, trebles and accumulators some of them are called Lucky 15, Lucky 31, Heinz, Super Heinz, Goliath. Source: Internet