Appears that the Z245 has a 48" deck; therefore, a set of A&I's 7 lobe XTH A-B1JD6017 blades would be what you need as they are made with Marbain. XHT (Xtreme Hardness & Toughness) blades feature a unique steel that incorporates boron, carbon, manganese, and other materials that ensure its strength. The blades are heat treated with a process makes the blades 25% - 40% harder than standard lawnmower blades, making them the longest-lasting, safest, and most impact resistant lawnmower blades on the market.
I used them until recently due a problem with A&I taking so long to respond to my emails and lying to about calling me. They are very good blades and usually last twice as long.
Hopefully I finally got that straighten out or they going to lose me as a dealer. It cost them most their sales to me last year. I went from buying over $3K yearly to $425. Another I have with is the way they did on shipping charges which can eat you alive below the $200 free level. I kinda mean now as I make double sure I buy at least $200. Example: $200.02 so I see a charge of $46 in shipping charges again.
I just starting this year's purchases. But it is going to be hard to meet the $2K yearly purchase minimum as I now got work out all the replaced parts of theirs before I can buy their parts again. Plus they have another problem as most their parts are higher than their competitors. I also had a problem that I could never get straighten out about their after market v-belts they all come in shorter than the stated sizes. I just had quit buying them even though they were good belts due to the sizing issues.