I've been using JSB Extra's in my S410's for years, and I've noticed that the old tin's had like a price tag showing the pellet diameter. When I bought my last batch they had changed the tin design, and the tin's didn't have that diameter tag.
I checked JSB's site and I see the Exact Jumbo's come in 5.50, 5.51, and 5.52. my old ones were actually marked as 5.53.
So the question is, how does someone order a specific size of the JSB's? Pyramyd shows the diameters but only offers the Exact Jumbo's in one.