100 Pack, 5/16" x 3" Galvanized Carriage Bolts, Designed To Fasten A Wooden Face To Either A Wood Or Metal Frame, Its Flat Head Is Designed To Eliminate The Need For A Washer & Provide A Semi-Flush Finish To Applications, The Square Underside Of The Head Is Self-Locking To Eliminate Spinning & The Need For A Driving Tool, The Galvanized Finish Provides Optimal Rust Prevention But Can Be Chalky In Appearance.