This custom narrow axle with axle nut are designed specifically to be used with 39mm Tapered Lowers when used with Lowbrow Customs 39mm Narrow Trees. The end result is a super custom, narrow & clean 39mm fork. For added performance take it a step further with the matching Narrowglide Fork Brace made specifically for use with our Narrow Trees. This ties your Fork Lowers together so they act as one unit, improving handling and cornering performance.