You are purchasing a Defender, Discovery 1 & Range Rover Classic Rear Trailing Arm Stainless Steel Fixing Kit
A4-80 is the equivalent of Mild Steel 8.8 high tensile bolts
Kits Consists of;
6no M10 A4-80 x 30mm Hex Head Bolts
12no M10 A4 Flat Washers
6no M10 A4-80 Nylon Nuts
2no M16 A4-80 x 100mm Hex Head Bolts
4no M16 A4 Flat Washers
2no M16 A4-80 Nylon Nuts
2no M20 A4 Flat Washers
2no M20 A4-80 Nylon Nuts

You have all the fixing to fit;
Both Rear Trailing Arms