PI-1 Alloy 45×45 Threadless Headset The PI-1 Alloy 45×45 headset has an aluminum top cap, upper bearing cover, lower race and upper and lower cups. All-aluminum construction results in a lightweight headset. Each headset is fitted with super-smooth rolling, precision 45×45 sealed bearings. Because this versatile headset has 45×45 bearings, you can use the included cups and install it in standard frames. Or, leave the cup in the box, and use it as an Integrated headset. Available in anodized red, blue, gold and black, in 1” and 1 1/8” sizes.