Customers say these caps transform their collection cups into versatile pumping solutions. Many reviews mention easy compatibility with various pump brands, particularly noting seamless connection with Spectra models. The caps allow hands-free pumping while maintaining discretion. Users appreciate the convenience of switching between different pumps without needing additional accessories. Common feedback includes praise for the simple attachment process and the ability to use collection cups more flexibly. While most find them secure, a few note careful handling is needed when transferring milk.