Legend 20 24 Holes Fixie Hubs Fixed Gear Bicycle Single Speed Bike Bearing Hub For Flat Spokes With Sprockets And Lock Ring - Bicycle Hubs - AliExpress
Boost is the WORD for new Single Speed hubs from PAUL - Bikerumor
ELITE “BOOST” MTB SINGLE SPEED CASSETTE HUB – Profile Racing
Amazon.com : Bibike Single Speed Conversion Kit 16T/17T/18T/19T/20T/21T/22T/23T Single Speed Fixie Cassette Compatible with Shimano Sram : Sports & Outdoors