I used structural screws which hold up to 800 lbs per screw. They went in perfectly and I feel completely safe sitting on my swing without worry of the screws coming out. https://www.homedepot.com/p/GRK-Fasteners-5-16-in-x-4-in-Star-Drive-Washer-Head-RSS-Structural-Screws-100-Pack-772691122254/301878339?MERCH=REC-_-pipsem-_-301878329-_-301878339-_-N
The manufacturer recommends 3-inch long 1/2" lag screws and flat washers for mounting in wood. These did not come included in my kit.
The mounting plate is 2" x 5.25". The eye is 1" diameter. The 1/2"-diameter mounting holes are 3.75" on-center. Manufacturer recommends 3" wood lags with a washer to mount.