GM Cowl Panel To Reinforcement Plate & Engine Splash Shield Retainer (GM # 94051993) - Package of 30 GM Cowl Panel To Reinforcement Plate & Engine Splash Shield Retainer Head Diameter: 14mm (9/16") Stem Length: 16mm (5/8") Fits Into 6mm (1/4") Hole GM # 94051993 (Geo Storm 1990-On)