Spiral Back-Up Ring SPR has temperature tolerance range of –70 to +260 °C, with primary function of covering the thrusting gap on ISC O-Rings radial sealing. It features a protective scheme of leaving a single turn of the spiral to support the ISC O-Ring in cases of severe thermal modifications. This back-up rings are versatile due to its adjustable size, enabling a wide array of fittings to the system.