These holders are for laser diodes of this type:
https://pt.aliexpress.com/item/32891622630.html?spm=a2g0o.detail.1000015.1.74b8768ebZIXaz&scm=1007.14452.155082.0&scm_id=1007.14452.155082.0&scm-url=1007.14452.155082.0&pvid=51b8362f-47fd-4c39-aa92-9c2895c5e956
for use in optical experiments.
