Picked up one of these out of curiosity, didn’t have high expectations but it does seem to work well enough with the Hario 02 and Kalita Wave 185.
Bloom through the centre section, then later pours using the outer ring.
It only took a couple of brews to get ball-park, then a little fine tuning.
So far with the Hario 02, I’m just over 2 turns on a Feld v1 at 2 turns plus 3.5 on the dial, (31.5 total, 2.25 turns). 13.8g dose.
Bloom 40g tiny shake, at 0:40 add up to 120g in about 20s, at 1:20 add up to 200g.
With the Kalita 185, same grind, bloom 40g/40s tiny shake, then 40g every 40s up to 160g, then 50g last pour.
All water poured with a Buono kettle.