The Buren (now Hamilton/Buren) Micro-rotor was the first patented automatic wristwatch movement to eliminate the sizable external oscillating weight inherent to most automatic winding watches. Instead, it utilized a much smaller weight that was entirely integrated into the chassis of the movement. This design allowed for a substantially slimmer automatic watch that still retained a center sweep second hand. The Micro-rotor concept was also conceived by Universal Genève for use in their Polerouter series of timepieces during this same time. The official title of "first Micro-rotor movement" is still in dispute among some horology aficionados, even though Buren patented their design in 1954, and Universal Geneve applied for their patent in May 1955.