Don't want to repeat everything that I and others have posted on the topic of Ddave adapters. Here is a somewhat shorter version. Feel free to differ:
The glass heating element of the EQ is an 18mm female which makes it compatible with nearly any other 18mm Male pieces out there. (One of the reasons why there is over 300+ pages of posts to this thread.) The cyclone bowl that comes in the box is well designed for the EQ. The right thickness of glass, the correct dimensions and honestly the more constant temps it is able to keep. Also, The width of the bowl doesn't block the airpath going to the fan and electronics. I would even give consideration of the volume of space inside of the cyclone. It really does work great out of the box and should be a
template to work from if you are considering new kit of any kind.
Ddave is essentially a design change on the bowl. It is usually a shorter glass piece that resembles the cyclone bowl. The middle screen is generally closer to the heating element and presumably the elbow piece is closer to the action as well. So this all allows for more
radiant heat which tends to cause the more visible vapor.
However, buying a simple squat 18mm to 18mm isn't necessarily a solution. (I made that mistake even after some research.) If the new piece has anything lacking that the cyclone bowl is designed to do well. Then you just bought a downgrade.
Also the type and thickness of said glass is a factor when keeping a constant temp. (Also another reason to allow adequate time for that glass bowl to heat up before using.)
As for me, the first adapter I bought
looked perfect in the picture. It is one of the $9 ones sold on Ebay and DHgate. But I never got the
actual outer and inner dimensions before buying and ended up being wrong on all three counts. The thickness of the glass, The center width of the outside dimension was too wide which would have blocked the airpath, and
even the larger amount of air volume inside the adapter made this a FULL downgrade. For $5 more I could have had one made closer to my specs. You get what you pay for. But for a few dollars more, you can be that much choosier.
No worries for me tho, I have since then re-purposed that $9 adapter to make all my portables vapes into whip vapes.