Sleeve Gear Bearing

AN shows a standard bearing and a shielded bearing

What's the purposes or advantage of one over the other.

MichaelB said:

AN shows a standard bearing and a shielded bearing

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What's the purposes or advantage of one over the other.

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A single shielded output bearing with the shield to the outside, part A2/316 was fitted to earlier Norton gearboxes, not Commando.
There's nothing to be gained by using a shielded (not sealed) bearing as the bearing is already shielded by the sleeve gear in my opinion.

It would seem AN no longer knows the difference between shielded and sealed because their "A2/316" appears to be a single rubber sealed (1RS) bearing and not the metal shielded (ZZ) bearing in the 04.0098 inset picture although a 1RS bearing is probably a better option for earlier Norton gearboxes.

i think it may be a case of what is available in 2022 the nominal brand 2RS version seems to be the only bearing which can be supplied by bearing factors
stick a spike in and pop out one rubber it becomes a 1RS

O.P., you should be EXTREMELY CAUTIOUS about the bearing.
The fact that it is offered for sale by a well recognized company is no assurance it is fit for purpose. The fact that "sealed" & "shielded" bearings are being described inaccurately is a red flag as well. (
The sleeve gear bearing I was sold had an insufficient radius to seat properly on the gear. (BIG problem).