You are purchasing a Defender & Series 2 & 3 Rear Crossmember Stainless Steel Fixing Kit
These are like for like on Defender TDCI rear cross member but in Stainless Steel
A4-80 is the equivalent of Mild Steel 8.8 high tensile bolts
Kits Consists of;
4no M8 A4-80 x 20mm Hex Head Bolts
10no M8 A4-70 x 30mm Pan Head Bolts
4no M8 A4 Spring Washers
14no M8 A4 Flat Washers

You have all the fixing to fit;
Bolt Rear Tub to Rear Body Mounting
Rear Body Mounting to Chassis