The fork tube caps / nuts are one of these items

and a disc lock can help deter would be thieves

Included are:

leaving 3-1/2 inches of freeplay

Radius Breather Bolts for Harley-Davidson Evo - Brass Subcategory_Patches The fork tube caps /Radius breather bolts from Lowbrow Customs feature an innovative design with 5 ply sintered stainless steel mesh, providing the proper breathability for your motor while keeping a slim profile and a completely custom look. An internally broached allen allows for a quick and hidden installation method, with the stainless breather element and circlip finishing the job. A perfect match with your choice of air cleaner and carburetor support bracket, these