Hi 

Thanks for the question, it is a little confusing you should be using the same size bolt as rawl plug.

But as you are drilling into masonry and with such a large bolt i would suggest using an anchor bolt or expansion bolt instead of a plastic rawl plug.

M12 x 80mm Rawl expanding bolt anchor with steel wings and threaded rod projecting 15mm, for heavy duty fixing heavy loads in hard and reinforced aggregate of a minimum depth of 100mm including hollow core block. Fixing requires 20mm SDS drill bit and a minimum hole depth of 85mm.

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