There is a lot going on with this Kel-Tec Sub2000 Gen 2. First it is a modified version that is now a takedown model. While not approved by Kel-Tec and would certainly void any warranty, it is an interesting design. While the concept of a takedown is intriguing on other guns and practical for some cases, it does not seem to be necessary for the Sub2000. The Sub2000 folds in half and is very compact. So having a removable barrel seems superfluous unless you are testing many different barrels on the same gun.
This barrel has been cut down and suppressed. If you notice the length is now the same as a factory barrel Sub2K. Unfortunately it loses its ability to fold and lock due to the handguard design and all the accessories on it.