Based on you mower’s model number, your mower requires a 17.25” blade with a 6 point star center hole.
Here are the Rotary brand numbers: https://www.rotarycorp.com/search?q=&l=15&p=1&s=relevance&pr=,&f=class:15;dimension:2_17.2500_1,4_6 POINT STAR_0
Stens...