As replied in the Picco topic:
Originally Posted by tdr170
Can someone lead me in the right direction, what is the diff between these three plugs.
Not sure if I will buy but the place where I can get the Sirio plugs is out of stock and there only 6.75.
But I still wondered after seeing this at Toro.
All 3 plugs in your attached picture are the same, so there is no difference there, BUT:
If you check the GRP site and look at there product information, you can read about the difference....