Do you still have to change them at the regular 3 monthly intervals as you do with the ordinary sediment/carbon filters?
They would generally last about 3 times longer than a standard triple pack of budget pre-filters. So if you use about 400 litres of water per day on a 4 day week on a 50/50 reject RO Ratio you would need to change this single pre-filter every 24 weeks which is nearly 6 months. In the same time you would have needed to change your average triple pack of budget filters (20,000 litre life) 4 times.
These filters really will save money in use and also will save on carriage charges as only one filter needs sending out once instead of 3 filter sending out 3 times.
To use in a standard 3 canister pre-filter RO unit simply take out all 3 pre-filters on the next change and screw back up two of the canisters empty and fit this single filter in the 3rd canister - then change after 75,000 litres. During this time you will also benefit from higher flow rates and less clogging which could save you further money on resin use as the RO could be performing at a better efficiency.
Clever chaps these people from Pentair.