BIANCHI speed strips or TUFF speed strips makes speed strips in various calibers and capacities. In certain TUFF makes a 6. .44 mag

Edit: just found one in Amazon. This is not an affiliate link

https://www.amazon.com/Tuff-Quickstrip-Orange-Round-Caliber/dp/B004WUNKM4

Not staggered like the one you mentioned but it's a good speed strip. I've used a TUFF strip for my TRR8 8x .357 mag