This is the HGUC Re-GZ.

In the show, it's called a Gundam imitation, and alongside the ν Gundam (which lacks a psychoframe), it's called a pathetic mobile suit, and generally gets a lot of bad things said about it (cries).
In reality, it gets pretty bad treatment except for the beginning 😭
This thing is part of the Z Gundam lineage, you know!?

In a certain robot war game, it's a bridge to the ν Gundam, and it's a fairly useful mobile suit that can fly and transform into a mobile suit.

Gundam look-alike | らんど's Gunpla works