It’s Calcium Hypochlorite. It’s a massive pain in the ass so please don’t use it. Hard to dissolve in water and leaves white residue everywhere.
Keep looking, you’ll find a supplier of sodium hypochlorite. Sometimes it’s referred to by different names, try asking for:
Whatever name the salesman calls it, check the MSDS and it will say “sodium hypochlorite” and list a % strength. 16% is the maximum possible, 10% is the minimum that you can use for pressure washing.
If it’s really hard to find, you will also need to check the manufacturing date. If was made a couple months ago… it lost some % strength and is of limited use to you.
Let us know how you get on