This collection carries two Axeon reverse osmosis membranes and one accessory:
The numbers in a membrane's model name tell you its size. The first two digits are the diameter and the last two are the length, so a 4040 is 4 inches by 40 inches and a 2514 is 2.5 inches by 14 inches. Most RO membrane brands use this convention, which makes it easy to match a replacement to your existing housing.
Not sure which membrane fits your system? Call 1-800-277-3458.