I just found this out today. You get free 3GB for 15 days if you have a visa infinite card and 1GB for 15 days for signature cards and you can add unlimited amount of cards to use multiple times.

you also get 30% or 20% off if you need additional plans

i have never used gigasky, i usually just unfreeze my google fi number when leaving the country but it never hurts to try esp since its free