Here is a basic step by step look at two methods for tying weed guards for flies used in structure. The first one is a double wire weed guard and the second a single mono weed guard. The gauge of the wire or mono is dependent on the size of the hook and it's gape,especially with mono complete loops. I use 40 lb Stainless Steel game wire for both single and double guards and 25-35lb med-hard mono on mono guards. Here are examples of a single and a double wire weed guard and a single mono guard.