These 5.5mm diameter springs are made from shape memory alloy. At room temperature this spring is soft enough to pull out to approximately 50mm by applying a small amount of force. * When heated to 70°C by passing an electric current through it (or by other means such as hot water or a heat gun, etc), the spring contracts to its original length with a useful pulling force (equivalent to lifting a 0.5kg weight) * Length: 20mm (when closed) * Supplied singly https://elecena.pl/product/27205926/rapid-smart-niti-spring 2024-11-10 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2025-04-02 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2025-04-16 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2025-05-02 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2025-10-05 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2026-05-20 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2026-07-05 https://elecena.pl/product/27205926/rapid-smart-niti-spring 2026-09-14