These nickel plated brass lacing needles are great for the Manny Method of joining cord. The 4mm size is great for 550 cord. While a slight smaller diameter than our Stainless steel or Aluminum needles, these will slide through the sheath of 550 cord very easily. You'll need to cut the cord on a slight angle to get it into the back of the needles, but other than that, cord fits perfectly. Get a set today and start joining cord the Manny way.