Korkers Greenback Men's Felt Boots Are Packed with Features which ultimately provide superior performance unrivaled grip and reliable comfort so you can focus on the fish (or lack thereof) and not on your feet. What We Really Love About the Greenbacks so this is it that they are equipped with the Omnitrax replacement sole system and are fully equipped with a felt sole. However, Greenbacks are compatible with special Korkers replacement soles so you can adapt the grip to the needs of each river system