The fly on the left is tyed with two strands of silk (thicker abdomen).
The fly on the right is tyed with a single strand of silk (thinner abdomen).
Brown Sugar Soft Hackle
Hook - Fulling Mills Model 35005 / Size 12
Thread - 8/0 UNI-Thread (Red)
Hackle - Hungarian Partridge (dyed brown)
Abdomen - Lilith Li Chinese Silk (Golden Brown)
Thorax - Wool-Ease Dubbing (Walnut/# 127)
(*) Optional Addition - a fine gold wire would make a nice tag/rib & added durability