About this item 9 Pieces of 9 Height Size.This headset spacer kit contains 9 different height sizes: 1 mm,2 mm,3 mm,5 mm,8 mm,10 mm,15 mm,20 mm,30 mm. Smooth incision edge offers high tightness.Small size spacer let you have a more precise height adjustment.You can combine them freely to meet your different needs. Made of woven carbon fiber,nice appearance,lightweight and well temperature resistance. Compared with aluminum alloy bike stem spacers,it’s more hard,better strength,more friction resistance and high corrosion resistance. Inner diameter is approx. 28.6mm,external is 34.9mm.This headset spacer set fits for 1-1/8″ bike headset stem.Universal for most bicycle,like mountain bike,road bike,MTB bike,BMX and etc.