Boss shoulder too small?

[Will_s87]

Is this the normal size for a boss shoulder? I bought a boss adapter but it appears to be too big to fit in the hole.

 

[algas]

Normally a rubber bung fits in the boss so makes up the difference

 

[muggles]

There isn't a "normal size" - each pipe manufacturer has their own size, so you need a boss adapter from the same manufacturer as the soil pipe fitting