G1 g2 etc. Is basically just just a designation as to what generation the jacket is. Typically the basic design of the jacket remains the same. For example the charge jacket always has a removable liner. However, you may see some material changes and appearance changes. Such as color patterns. The charge was a very nice jacket. And a very warm jacket. Even with the liner removed you still have some insulation in the shell. Maybe not the best mountain jacket, but a great cold weather trail jacket. Hope that helps.
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