(a) Adequacy. Adequacy of a showing of interest refers to the percentage of employees in the unit involved as required by §§ 2422.3(c) and (d) and 2422.8(c)(1).

(b) Regional Director investigation of showing of interest and Decision and Order. The Regional Director will conduct an investigation if deemed appropriate. A Regional Director's determination that the showing of interest is adequate is final and binding and not subject to collateral attack at a representation hearing or on appeal to the Authority. If the Regional Director determines that a showing of interest is inadequate, the Regional Director will issue a Decision and Order dismissing the petition, or denying a request for intervention.