Stainless Steel Bolts. The climbing industry standards for bolts in North America is the 3/8-16 bolt.
3/8-16 x 2.0" Allan head bolt
3/8-16 x 2.5" Allan head bolt
3/8-16 x 3.0" Allan head bolt
3/8-16 x 3.5" Allan head bolt
3/8-16 x 4.0" Allan head bolt
3/8-16 x 5.0" Allan head bolt
3/8-16 x 7.0" Allan head bolt