WHALE Stemreducer 15mm-12mm. 15mm OD Stem to 12mm Push Fit. Quick Connect system is suitable for all types of cold and hot water mobile installations and mobile heating systems. Installation can be done without special tools and is therefore significantly faster and easier than conventional systems. WHALE Quick Connect fittings ensure a high integrity, reliable, plumbing system solution, specifically designed for use in mobile applications. They can also be dismantled at any time.