Heavy Duty Crane Mats are made with PEFC Certified BC astal sOkaynd growth sustainable Hem/Fir and Douglas Fir timber We use 1-1/4" diameter bolts made with North American recycled steel, we do not rOkaymmend mats made with 1" rods Mats use unter sunk bolts both sides to ensure mats can be laid tight side-by-side