Not all clen is the same, with certain compounds you can pretty much guarantee what sort of results you will get.
Clen is not like this, it really does depend on the company, the raw product and how you use it.
Kalpa clen is 40mcg per tab which would explain why strong was getting the shakes on a couple, with me I use up to 160mcg of Kalpa Clen(but normally stick with 120mcg)
If I use original Bulgarian pharma grade clen I need to take it up to 200mcg to feel the jitters, then if I take the chinese clen its 80mcg and I'm shaking like Elvis.
All brands are not equal when it comes to Clen.
https://www.hypermuscles.com/f23/clenbuterol-1996/