Masport/Logaire

245 x 145 x 25 rebate or no rebate  Weight approx 1.95 kg - $20.93
250x150x25 rebate or with no rebate $22.08
250x115x25mm rebate $16.91
250x65x25mm rebate $9.55
225x145x25 with rebate $19.21

Check you firebricks to see if the fire brick has a rebate on one of the top ends of the firebrick.