It's the bearing on the not-engine side of the rear wheel shaft. It appears to be a deep groove ball bearing.
There wasn't any play in the wheel when it was mounted.
Hypo, you should always run the best you can. It's the best policy.
I'm just a dyed-in-the-wool cheapskate.
If it has been install and seems to be within specs for runout, it should be good.
Possibility is, it may wear out quickly.
When bearings exceed specs, everything on the shaft they support wears faster, or,
The bearing may decide to wobble out whatever it is mounted within.
This could mean replacement of Much more expensive parts ! and that same bearing, once again.
It's your call. None of us can ever really see what's actually going on so we will tell you our tall tales and discuss philosophy.
...I RX'd a timken bearing today, with other parts, and the cage has been dented in transit because the components in the parcel were not protected from each other. Just now I sent them an email telling them I Would give them a 5 star rating, but they owed me a rebate because I'll need to ride to the next town to purchase another bearing, now at a higher price. (It's for my rototiller, and has caused seasonal problems because it was out of service.)
I won't use the funky bearing because I don't want to take the messy ole TroyBilt apart ever again !
Best
redk