Locked hands style
Locked hands style is a technique of chord voicing for the piano. Popularized by the jazz pianist George Shearing, it's a way to implement the "block chord" method of harmony on a keyboard instrument.
The locked hands technique requires the pianist to play the melody using both hands in unison. The right hand plays a 4-note chord inversion in which the melody note is the highest note in the voicing. The other 3 notes of the chord are voiced as closely as possible below the melody note, which is the definition of a block chord. The left hand doubles the melody note one octave lower.
To achieve this result, the pianists's hands must be placed close together on the keyboard and both hands move simultaneously in the same direction. To an observer, the pianist's hands appear to be locked together.
The technique had been employed by numerous jazz pianists prior to Shearing. (Phil Moore, Duke Ellington, Count Basie and Red Garland), Shearing said he was first exposed to it through Milt Buckner, the pianist for Lionel Hampton and the musician considered the originator of the technique.  This harmonic technique was also used in the horn arrangements of Glenn Miller's big band and is a staple of modern big band arranging. 
- Baerman, Noah (2004). The Big Book of Jazz Piano Improvisation. Alfred Publishing. pp. 94–5. ISBN 0739031716.
- Owens, Thomas. Be Bop. Oxford University Press. ISBN 0-19-510651-2.
- Block chord