WITHit fitbit charge 3 fitbit charge 4 bands wrist bands watch bands black blue

WITHit fitbit charge 3 and fitbit charge 4, three bands, black blue and off white colors, blue and off white band buckle, black band is stainless steel mesh, blue band is sport silicone, off white band is silicone, never wore, took blue and off white band out of package but couldn't figure out how to secure it to fitbit watch, measurements in pictures