What needle length for my delts?

[AlexDavis43]

Does that also prevents glass shards? I have a few vials in ampoules, but been to scared to use them incase of glass that gets drawn up I can't see.

I use these for amps, mainly because 1.5 inches and a blunt tip allows for the extraction of more oil.

Always looked like a lot of residual oil in the amp after withdrawing with a standard tip needle.

Bonus: less glass in your ass