Helloo people, i bought a wiseco oversize piston for my bike a few weeks ago. the inside of my cylinder is magnetic! and you can see a really light bronze colour ring on top of the cylinder so i thought it was sleeved but when i took it to get bored the guy said it was plated?

i thought plated cylinders wernt magnetic really need to know if it sleeved or not, dont really trust the guy who said it because hes not a proper mechanic? Some help reall would be usefull! Cheers