We bought two of these for our dogs about a month ago. We spent the extra money because the collars were supposed to be better on these units (in comparison to the basic model). The collars are the worst part of the product. The collar material is slick, and it allows the buckles to "slide" loose shortly after putting them on, rendering the unit ineffective because the metal prongs are no longer in contact with the dogs' necks. I work nights, so I have to sleep all day, when our dogs are awake. We bought these in hopes it would help control our hound dogs' barking at the mailman, solicitors, UPS guy, etc., while I sleep. In less than 15 minutes of putting them on, they have shaken them loose and all they are is an extra collar (I think they have actually figured this out!). Also, the metal prongs that screw in have become loose and fallen out a couple of times. After tax, we spent about $150 for the pair of collars, we were very disappointed because I figured the Petsafe name would have brought with it a better degree of quality.