I ended up the victim of 6 50 bills this past week but since I dragged my feet going to the bank I have no idea who they came from or where.
They look real are printed on bleached washed 1s and 5s so they are on money paper but they are fake they look like the old 50s
Be careful even that pen would not notice they are fake the bank took them from me so I'm sadly out $300 just be on the look out for old money n b careful

The owner of one of the agencies I used to work for used to use a UV LED light on all her money. It was a little keychain light she got online for like $5. Money has a strip that glows under UV light, a different color and location for each denomination. It works on bleached bills, unlike the pens, and it's easy to quickly scan a stack of bills with it.

yes ive seen that
honestly Ive never had an issue til now so I was a bit slack
I am now on my game with it.

Thanks for sharing. I will be investing in this today.

about your bad experience.  Thanks for sharing, I never thought about checking my money until reading this.