Hex bolts

[Deb04]

Is there a standard size for the hex bolts that hold down the safety cover for in ground pools. I measured it at 5/16" and bought an Allen wrench, but it's quite a bit too big.

 

[JamesW]

Usually 1/4".

 

[wrigbay]

Mine are 1/2 inch

 

[JamesW]

The Allen wrench is usually 1/4" and some are 7/32".

What is 1/2"?