The BFS1421 and BFS1422 are designed to hold the blade below the moulding and prevent the blade from cutting into the encapsulation. A permanently-attached, self-lubricating nylon spacer lets the blade move easily back and forth while holding the blade under the lower lip of the moulding or encapsulation. All blades are made of a specially-formulated steel that is hardened and then tempered using a cold molecular-aligning process. This makes the blades very flexible. Each blade will easily remove over 50 windshields when used according to directions. Made in the USA.