Vyair only sell a high pressure membrane.
Most of the others sell the membrane in high pressure (HF4) and low pressure (HF5). Choosing the right one will depend on your water pressure if you don't have a booster pump. (HF5 is the one I use on 50 psi water pressure).
The HF5 is more expensive, but with these membranes it's all about buying the right one.
The other thing is to ensure that you use the correct prefilters. Suggest Fiberdyne carbon block from Gardiners with an sediment filter first if your tap water has a lot of sediment as ours does.