The Polypipe PolyPlumb Enhanced 15mm Plastic Pipe Stiffener (INCERT15) in black is a high-performance insert designed to strengthen and support plastic pipe connections in push-fit plumbing systems. Engineered with Polypipe’s patented In-Cert feedback technology, it provides a secure, reliable fit that ensures proper installation every time. Ideal for use with PolyPlumb fittings and Polybutylene pipes, it helps maintain joint integrity in hot and cold water, heating, and underfloor heating applications. WRAS and BS 7291 approved, this durable stiffener delivers long-lasting performance and professional results for both domestic and commercial installations.