Yes we all know I love undersized yoyos… so I’m want to stick around that. They’re the most fun and easy to throw. Anywhere around 53 diam or less. I doubt there are undersized bimetals with SE’s, but if so I’d be very eager.
Right now I want to find something that looks nice and is undersized. I plan to try finding some nice spiral SE’s. I will want something fun to throw them with, thanks!!
I’ve been a big side effects fan for a while now. The only bi metal yoyo that uses side effects I’m aware of is the Atmos Projects - Khuno which is definitely not undersized and reasonably difficult to find.
Side effects are incredible and are such a unique and satisfying feature to tinker with.
OD 54 is the smallest SE yoyo as far as I know
i would recommend the parlay, or a sudo, both are on the bst right how. of you like organics, and i believe they fit your size goal.
Rebirth and Reboot are 53mm. 54 gen 2 is 54mm.
54 had a notable diameter, but because it was the largest (so far).
Also, Kamuraiju at 54mm
Look up the Dietz on OD.
The Noma by Atmos is a sweet undersized SE throw! 52.6 mm and <60 g! It’s light, floaty, and organic.
Unfortunately, I think it’s sold out.
reboot and rebirth are fun. rebirth has some cool colors out there
I think the noma might be smaller!
second this one, Rebirth is amazing.
Yelets is a 52.6147 diameter
also, Zero gravity Janus is also pretty cool, if you want a something more micro at 45mm. It’s light and narrow so more oriented for modern responsive.
My recommendation, if you can find one is the luftverk daytona SE it’s 52.81mm diameter; my personal go to yo-yo. I like it so much I am always just considering selling all my other yo-yos 
I too, was going to recommend OD Rebirth!
The Parlay is a really solid throw and One Drop still seem to be releasing them all these years later. So they’re accessible and also reasonably affordable.
Haven’t tried a Dietz, but the Lab Experiment & Halifax are pretty similar and I’ve used both. They definitely feel & play like minis. If that’s what you’re after then maybe try to track one down.
Cascades have a good reputation (never tried one myself), but they’re usually a bit expensive. Prescriptions have a somewhat similar design (never tried one either!) but are harder to find.
Sakura SE and Lab Experiment #1 are just… incredibly rare.
1to1s are seriously so insanely wide that it feels like cheating. Probably not what you would describe as undersized. It feels like .
