Scooter BMX Bike Head Set Nut Adjustment Spanner To Remove or Tighten your Head Set 36mm nut on your Scooter or Mountain Bike. Ultra thin spanner with sizes 30mm 32mm & 36mm 40mm . Thin enough to fit around your scooter or mountain bike headset nuts. Its easier if you use 2 spanners, one to secure and one to tighten.