Looking for purchase links for this, reco by @methods :
https://youtu.be/YI3m5R6i3OU
a non-Amazon source would be great, don't mind if slow, may want to buy in bulk
a two-way version even better
Also a link to the crap one he mentions so as to know not to bother testing it, would be appreciated.
If there are other inexpensive units you want to recommend, based on personal experience, verifying against known good instruments
that would be fine, but please state that your post is not discussing these specific OP models
https://youtu.be/YI3m5R6i3OU
a non-Amazon source would be great, don't mind if slow, may want to buy in bulk
a two-way version even better
Also a link to the crap one he mentions so as to know not to bother testing it, would be appreciated.
If there are other inexpensive units you want to recommend, based on personal experience, verifying against known good instruments
that would be fine, but please state that your post is not discussing these specific OP models