The closed cup in this kit is too deep and if you just let the dynavap rest on the bottom passively during heating until the click (even just the first click), the flower will reliably combust resulting in wasted flower and the need to clean your dynavap for flavor. I see this mentioned in other reviews and forums as well.
To prevent combustion, what has worked for me is to actively position the dynavap in the cup for optimal heating using trial and error and pay close attention each time when using for repeatable results. Once you get used to it you can hold the wand at a an angle (about 45 degrees) and rest the dynavap in the cup at whatever optimal depth you discover and friction will hold it in place so you don't actually have to actively hold the dynavap. That's not how usage is described in their ad description or videos so I see this as a pretty major flaw in the execution of this VERY simple $30 item that seems like it should have easily been a home run. I'm really not sure the point or value of the open ended cup vs the standalone Wand.
Perhaps I can find a silicone spacer to improve performance but for a kit with two small pieces of glass for $30, I really shouldn't have to go on that search. Dynavap caps are very standard in performance so I struggle to see how iSpire missed hitting a home run on this design. If there actually is cap variability then this kit would be better and possibly approach worthy of half the retail price if it also included properly sized silicone cup depth spacers that allowed for depth adjustment (and worked in both the closed or open cups).
As things stand now, I don't recommend this kit.