Classic trance employs a 4/4 time signature, a tempo of 125 to 150 BPM, and 32 beat phrases and is somewhat faster than house music. A kick drum is usually placed on every downbeat and a regular open hi-hat is often placed on the upbeat. Extra percussive elements are usually added, and major transitions, builds or climaxes are often foreshadowed by lengthy "snare rolls"—a quick succession of snare drum hits that build in velocity, frequency, and volume towards the end of a measure or phrase.