Greenfield Products River Anchor 15 lb. The Tri-Fluke design of the River Anchor allows the flukes to penetrate the river bottom in soft and moderate conditions, or to engage rocks and structure in rivers and current. The 516-B-WLM River Anchor by Greenfield Products is a great all purpose anchor for lighter craft, or a great second anchor. Greenfield Products quality coated anchors have been holding America's boats for 60 years.