This is a direct part replacement for MD 369 Series, 500N, 600N Helicopters P/N LF612. However, this part is upgraded and made out of aluminum instead of plastic for extended durability. It also has both attachment bolt holes on the interior side for easy installation and removal. This component is FAA approved. Purchase a shipset (4) for $1000 or a large shipset (6) for $1500. Use coupon code SETOF4 and SETOF6 to apply the discounts in your cart.