Designed to outlast the completion these replacement knives and blades are designed specifically for your Kolbus HD150 or HD151 trimmer. Available for both the front or side cutting positions we carry blades made of high speed steel or inlaid with tungsten carbide. The top front blade is 22.047" long and has ten holes and the top side blade is 15.94" long and has 9 holes. Double check to make sure that these specs match your existing knives. If so, what is stopping you from ordering today?