The B1669-4 is a pressure change assembly with a 1/8-inch orifice designed for various series of inverted bucket traps, including 211, 310, 800, 811, TVS-811, 880, 881, 981, and EM series manufactured by Armstrong International. This assembly ensures precise pressure regulation and reliable operation, maintaining optimal system performance. Its high-quality materials and precise design make it an ideal choice for maintaining and repairing pressure change assemblies.