Deda hss alloy spacer pack 3pcs the innovative deda hss system headset stack spacers they work exclusively with the deda hss headset to allow you to install oversized spacers directly between the hss headset bearing cover and its top cover both not included to give an equal diameter steerer from headset to stem unlike the traditional systems included in the box are 3 spacers a 3mm 5mm and 10mm the spacers are designed to go under the headset top cover giving the bike a flush look t