Uprights are 3 x 3 posts x 4 rebated for the cross beam 18" buried in postcrete . Main cross beams 6 x 2 attached by M10 bolts. 8 @ 5 x 2 above skew nailed and 8@2 x 2 atop that. We thought it a nice idea later to put a swing on the main beam for the grandkids 4-6 yrs weight approx 20-25kgs. I...