Phil Wood Sealed Standard 1-1/8" Threadless Headset - Red 1-1/8 - 1-3/8 520mm The ACS Maindrive headset features

The ACS Maindrive headset features hybrid aluminum and steel construction

Comfortable padded seat featuring a durable fabric cover

Color: Black w/ Silver Machined Sidewall

This will fit 3-piece cranks that have 19mm spindles

We do not recommend using 18x1 tubes in them

Phil Wood Sealed Standard 1-1/8" Threadless Headset - Red 1-1/8 - 1-3/8 520mm The ACS Maindrive headset featuresThe Phil Wood headset development was inspired by the company's great customers who encouraged them to release a headset and helped duting years of testing and development. This headsert is manufactured with US produced stainless steel and 7075 aluminum. It is engraved with a script Phil into each stem cap and hand painted just like the Phil Wood hubs. Each headset is machined in house to the same high quality standards applied to all of Phil Wood