Simms Headwaters Pro BOA Boot - Vibram Sole. BOA lace systems offer precision fit by ensuring that the entire lace tightens evenly. Finely tune the correct lace tension for your foot with the turn of a dial. Simms Headwaters Pro BOA boot are an excellent alternative to traditionally laced boots. The added stability provided from the BOA lace system combined with durable nubuck and scratch rubber construction is a comfortable and long lasting combination.