STI Magazine 10 round restrictor. Make your standard magazines into restricted magazines for matches in Australia, Canada and other countries with overbearing and restrictive firearm laws.
This fits in mag bases that have been machined out (so it drops into the base and holds the magazine in place).
If you need modifications to fit your mag base please let me know and I'll see what I can do (time permitting).
This has small diameter curves so you may want to slow the print down a little.