When we first saw how these shrank under hot tapwater we just said WOW !!!  These coils are AAA Triple A Grade Highest Quality Nitinols that are used for Avionics 'fly by wire' and Industrial Robotics Applications.  These offer the VERY LOWEST Activation Temperatures and Current Requirements of either 45°C or  2 Amps Current and we  hand choose the MOST SENSITIVE that react at or BELOW 45°C and UNDER 2 Amps Current.  Our latest shipments triggered a return to their unstretched size at an amazing low uniform temperature of 112.4°F and returned to about 110% of initial size - really REALLY remarkable to see.  Nickel Titanium and Nitinol on the web as well as on ebay is mostly dental wire composition, which is off-spec Nitinol 55 or about 1/2% off or more from the prime composite which is famous for the PING and ZING and ZIP that the finest Nitinol 55 is known for and that ' SNAP' Back to its original shape when heated or exposed to electrical current.  These will pull to about 6 inches or you can bend them into any shape and when you heat them very slightly, or expose them to 2A of current they Whip Back to their original size of just over 1 inch in under 1 second time.  The price here DOESN'T BEGIN to reflect the quality.  YOU MUST HAVE AT LEAST 10 RECENT HISTORY POSITIVE FEEDBACKS TO BID ON THIS AUCTION, unless you contact us PRIOR to placing a bid with YOUR NAME, YOUR ADDRESS AND YOUR LISTED PHONE NUMBER.  Acceptable forms of payment are either PAYPAL or PERSONAL or COMPANY CHECKS or MONEY ORDERS or CASHIER'S CHECKS.   Shipping to the 50 states is: $5.00.  Shipping to Canada is $5.00.  Shipping to U.K., Europe, Australia / New Zealand is $13.50 regular Airmail REGISTERED MAIL - NO INSURANCE ON PACKAGES SHIPPED OUTSIDE OF THE U.S..   >>>Shipping on this cannot be combined with any other item purchased from me on a concurrently running auction<<<.  These are REALLY SOMETHING to experiment with and are Very Valuable for lab-accurate and engineering applications and every one we sell is CERTIFIED and NUMBERED STOCK.