Medela Spare Valves and Membranes, 2 Sets, Authentic Medela Replacement Parts Designed for All Breast Pumps Except Sonata and Freestyle, Made Without BPA

The valve and membrane are what effects suction. Aside from melting or crushing the piece in your picture, ot shouldn't be causing problems. Edit: but you don't need to boil them. Warm soapy water is sufficient.