M5 x P0.8
A hole is 4mm
This is made of Carbon steel & black oxide.
This PIn is not special,just same as PDI Bipod base.
This one fit to PDI Modular stock to put Harris Bipod.
About shipping cost:
This parts is not so heavy,so almost no changable for the shipping cost.
But our system,when you purcahse a lot,the shipping cost will be expensive.
Giving order, we fix the cost to correct price by 2nd e-mail reply.
Don't worry about it. If you feel an expensive the cost,please tell us about your cancel.
We accept anytime.