Heavy duty 3000° F fire brick 

known as “splits” for being Approximately half of a regular or standard firebrick. 
these measure 1.25” thick x 4.5” x9”

most often used on forge floors as they are highly flux and abrasion resistant . 
these are difficult to ship as they are heavy and fragile. It’s best to use a courier rather than Canada post (my website only uses Canada post at this time) contact me at spc@frontstepforge.com to make arrangements