The popular Invert Mini markers were revamped into this new version in 2014. The Mini-GS marker is characterized by some reshaped plastic components along with some mechanical changes meant to increase reliability. The marker use a similar internal layout compared to the classic Mini and Axe.
Main Enhancements from Mini to Mini-GS:
Redesigned regulator mounting method
Mechanical on/off ASA (similar to Axe Relay ASA)
Integrated foregrip with rubber outside cover
Battery spring clips instead of 9v connector snap
Plastic feedneck body using a boss-latch connection (note: the body still has feedneck threads)
Smaller profile bolt endcap
Microswitch trigger similar to Axe
Rubber board cover; potentially make upgrading mainboards easier
The following parts are identical between classic Mini, Axe, and Mini-GS:
Top air transfer tube
Empire markers use a mixture of both metric and 1/16" AS-standard o-rings. Sometimes you can swap one for the other, but it often requires experimentation because the new o-ring will have a looser or tighter fit compared to the factory o-ring. For instance, the firing poppet's o-ring can be swapped with a 13/90 instead of the factory 2x10-mm ID o-ring.