This is the free version. If any maintenance is required you will have to pay for both the materials and the time.
This is the medium and most popular version. For $5.00 a month, you can get the materials for free, but the time will not be. Alternatively, you can have the materials shipped to your door for free and and do the installations and repairs yourself.
This is the highest and most expensive tier. for $10.00 a month, you can have the the repairs and materials are provided for free at anytime during your subscription