Pre-cut out of .05 foam these offer the perfect combination of silhouette and added flotation. The Spirit River Mayfly Pre-Cut Wing is a fly tying material specifically designed for creating realistic and lifelike mayfly imitations for fly fishing. When using the Spirit River Mayfly Pre-Cut Wing, fly tyers often experiment with different patterns and colors to match the local mayfly hatches and the preferences of the target fish species. Attention to detail and precise tying techniques contribute to the effectiveness of the artificial fly on the water.