Planning second grow in coco. Need help

I’m In the middle of my first grow In ffof. I want to start my second grow using coco. Not sure how much to order or which one to order. I need enough for 3 five gallon fabric pots. How much would I need and should I mix with perlite? Any links on amazon? I have fox farm trio and calmag. Thanks!

Two bricks ball park estimate. I would recommend some perlite, but not more than 20%. The amount of perlite is a personal preference. Maybe @dbrn32 can chime in with how much he purchased on coco.
I couldn’t find the smaller packs, but here’s a larger order with some commitment.

CANNA Coco Brick 40l Expandable Natural Plant Medium Soil Substrate, 40 Liter Expanded - 8 Liter Dry, Reusable (10)