Hi Vilinsky,
With the purchase of the Guardian, your first year of service is free.
The following years from then on, the Annual Maintenance Service cost is $165 if you send it OTS, which includes parts and labor. You can see the repair rates here :
Repair Rates | Ocean Technology Systems
You can take the online class, which consists of a powerpoint to guide you through breaking down the mask and regulator to bare bones, then putting back it together. After the powerpoint, you will be prompted to take a 30 question quiz, and when you score 100%, you will be authorized to order spare parts and service the mask as a certified tech. The cost of the online class is $185- which includes your tool kit (85$) and the online class portion (100$). You can see the OTS Guardian Course Description here :
OTS Guardian Technician Course Description | Ocean Technology Systems
The class portion it will reduce your annual maintenance cost for the mask and regulator in the future. Once you become a tech, you can order a spare annual maintenance kit for $69- and perform any troubleshooting issues on your own if the need arises, which is nice if you are at a remote dive site that you can be self sufficient.
If you don't want to deal with any of that and you are looking for a Technician to take care of the Annual Service of the mask, you can check out our Guardian Service Locator. Just type in your address. You can check that out here :
Authorized OTS Guardian Mask Service Centers | Ocean Technology Systems
Hope this helps! Let me know if there is anything else I can help out with. Take care.