Park Tool HCW-5 Lock Ring Spanner 40-46mm Crank Bottom Bracket Wrench Fixed Gear 763477004055 | eBay
Park Tool Fixed-Gear Lockring Wrench HCW-17 – Dcbikes
Single Speed Fixed Gear Freewheel Wrench Tool – Dcbikes
Lock ring came loose on my fixed gear now my pedals will spin free from the wheel partially. From what I found online I need this special tool to tighten it but