At first I was in a hardware store known 3-letter and wanted to buy the nails there. Yet, it had nails from 20 mm length reasonable broad heads to keep the roofing felt also in place. Stupid if the roof boards are just only 18 mm thick. This one, however, have nice broad heads, are all intact, no broken goods or something, are well kept in the bucket and also cheaper than the hardware store. Thus unrestricted recommendation.
