The executive secretary of the Washington state association of elected county officials, upon written approval of a majority of the sheriffs in the state, shall file with the secretary of state a description of a standard uniform which may be withdrawn or modified by re-filing in the same manner as originally filed. A uniform of the description so filed shall thereafter be reserved exclusively for the use of sheriffs and their deputies: PROVIDED, That the filing of a standard uniform description shall not make mandatory the adoption of said uniform by any county sheriff or his or her deputies.