Short review for this one.
The submarine is a modular kit of marine-type parts that assembles into three different main modes, meant to be a model on its own, but mainly as an option kit for aquatic/marine themed builds, using other 30MM models.
It's a bit of a mixed bag of what works and what doesn't. The fins and sub-arms use simple 3mm peg connections, but the main 'body' and the saw-tooth blade use C-clip connectors and somewhat awkward parts that don't really fit onto anything else. The two "legs" (which can be used to literally replace the legs of a Portanova or other kits) use C-clip parts that once you take them off, are stressed. Because C-clips are not a good connector part.
The kit also includes a unique two-piece head with large mouth and side vents, but no clear eye/visor parts.
I've been able to use maybe half of the parts on other things, like the various fins and covers, but the main parts use a bit too awkward connectors to really be useful.