Puzzle Piece Heart Autism Awareness Silver Stainless Steel Pendant & Necklace Made of 304 stainless steel. 304 contains 18% chromium and 8% nickel. Pendant is a jigsaw puzzle piece with a heart cut out. It has a high polished finish. Comes on 24” box chain necklace. It does not tarnish and will not need polishing. Stainless Steel is an easy-care metal that requires no extra maintenance. Stainless steel jewelry is easy to clean just by using soap and water. It is strong and durable.