Yes, that helps.
You will need the PRE-RO filter for the first stage and the TFM-36-A for the 2nd stage. Both of these filters are located here:
http://www.waterfilters.net/culligan/reverse-osmosis/Culligan-H30S-R.htm
The PRE-RO filter will need to be change most often. It should be changed every 3-6 months depending on your usage and water quality. The RO membrane should last about 2 years but also depends on your water quality and water usage.
Some systems have a small 6" post-filter that is also listed on the above page as Stage 3. Not all systems have this filter but if you have it, it will be after these two filters and is connected to the tubing. You will need to check your tubing to see if it is 1/4" or 3/8" to determine which post-filter you need. If you do have the post filter, it should be changed about once a year.
Thank you,
WaterFilters.NET