Don't trust your climbing wall project to just any old T-Nuts - insist on Zinc plated. Stainless steel is better but usually not worth the extra cost. Zinc plated metals resist corrosion for years and have no strength issues. Our T-Nuts are 3/8x16 with a 7/16 barrel depth - standard for most walls. We can get ANY amount you need, if you need more than what's listed - email us!