Questions about Seafrogs red Floating Arm 10"

I wonder if this Seafrogs GA-7_red floating arm 10" how long it is and how much buoyancy it has 400g or what. Again, it's hard to figure out because on most pictures the GA-6 is made with 300g. I currently have one with 900g but that's too much lift so I calculated that I only needed a 400g. But a length of at least 20cm would be good. LG