5/16-18 x 1-1/4" 馬車螺絲 | 鋼熱浸鍍鋅（100顆/包）

Put these on a heavy-duty swing set frame and that galvanized coating handles the weather really well—no rust after a month of rain. The threads bit smoothly into the wood without stripping, which I wasn't expecting with carriage bolts.

Installed a dozen of these on a temporary fence gate and the galvanized finish hasn't shown a hint of rust through two rainstorms. The square neck bit into the wood perfectly, which kept them from spinning while I tightened the nuts.

The rounded head sat flush on the wooden beam without splitting, and the hot-dip coating is thick enough that I don’t worry about rust. One hundred pieces in the box is a solid value for the price.