Before I get into the review, I would like to add that I have owned the Atmos Greedy, Pulsar Hellfire/Barbfire and now the Sia Topflow Atomizer, all three atomizers are basically the same design and all three atomizers suffer from the same "bottom airflow" leaking.
This bottom airflow leaking can be fixed by carefully wrapping one even layer of tape on your Coil in Painters Masking Tape. Done properly the coil should JUST fit snugly back into the atomizer, and fixes the issue of air leaking between the coil casing & atomizer and makes a HUGE HUGE difference when smoking on all three devices. Once done this thing hits like speeding freight train.
Also I am using the Optional Crushed Clapton Coils not the supplied "Bucket" coil. I previously owned the AVS Molecule RDA whose company designed the crushed Clapton Coils for the Sai. Alsona decent atomizer, but the Sai is still a step up.
Also on the topic of airflow, once I fixed the issue of the leaking bottom airflow, I blocked up one of two top airflow holes and it hits perfectly.
This is an excellent atomizer but needs a touch of tinkering to get hitting right.
That being said this still my favorite atomizer of all time, and I've owned/own EVERY single Yocan Concentrate Product, much of Atmos & Pulsar Concentrate Atomizers, a plethora of disposables, the Headbanger, the Brainfogger, the Stentorian, a ton of China made knockoffs.