The Avent Via 8 oz. Refill base is compatable with your Avent ISIS Breast Pump. These replacement bases are sturdy enough to reuse up to 3 times while being affordable enough to dispose of after just one use. Dispose or reuse - it is up to you. Pump directly into the 8 oz. bases and use the lid or adaptor from your Via kit (sold separately). Bases are great for storage whether you are at home or on the go.