Home default In some models, the gears are sequential; in the quieter and more efficient version, the gears are interlocking. In some models, the gears are sequential; in the quieter and more efficient version, the gears are interlocking. Pvc Pipe December 29, 2019 Share: Facebook Twitter Pinterest In some models, the gears are sequential; in the quieter and more efficient version, the gears are interlocking. ... Click to read moreOthers news: Another news: