M6 means the stainless steel pin diameter is 6mm(0.23"),suggest working load limit: 550lbs(250KG)
M8 means the stainless steel pin diameter is 8mm(0.31"),suggest working load limit: 1000lbs(452KG)
Material: 304 stainless steel
M6 outter size: L*W=2.28"*1.18"; M8 outter size: L*W=2.95"*1.52"
We also supply smaller size quick link hooks M5,you could find from our amazon store
Pls pay attention to size and load limit before you purchase
Design with screw to make connection firm and stable
Could be used for boating,sailing,hanging strong items,firm tents,firm truck and boat cover and so on
You have more choice to use at home,outdoor,in the garden,as we supply two size hooks M6 and M8
Package include:

2pcs 304 stainless steel M6 quick link hook ring
2pcs 304 stainless steel M8 quick link hook ring