DT Swiss Conical Thru Axles
About DT Swiss - Driven by the vision of becoming a worldwide known manufacturer of bicycle components, DT Swiss expanded its product range over the years. Today DT Swiss has established itself as a leading manufacturer of spokes, nipples, hubs, rims, complete wheels as well as suspension systems.
Usually flat or conical. This is the shape of the washer and should match your frame or fork.