Only a few manufacturers including Dodge, SKF, and Timken make unitized SN dimension metric units. However, our unitized SN is the only 100% compatible unit with standard SN5 in the world. Because the competitors use one size smaller bearings than standard SN5 bearings. Why? Because they use their adapter mount inserts which are same O.D. as their setscrew mount inserts although SN5 uses taper bore 222XX bearings with the adapters.
Please check https://www.crossocean.com/interchange-guide/#SN5 
The bearing sizes listed in red are smaller O.D. sized insert than standard SN5 bearings. For example, SN511 uses 22211 bearing and Dodge ISN511 uses their 22210 insert. You can see in the chart below as well.

Their center heights and mounting pitches of housings are same as SN5, so they use larger housings with smaller insert to mach the dimensions. Our insert bearing number is exactly same as SN5. The smaller O.D. size has reduced load carrying capabilities and may lead to shorter bearing life. 

The competitors would say SN5 bearings are oversized because of adapter sleeves. However, the long time SN5 users can't expect the same bearing lives to those unitized SN5 units. We use the standard adapter sleeves in our patented CROSSLOC™ and this is why we are 100% compatible with SN5.

We are trying to be competitive on price as much as possible even with one size bigger inserts than others to achieve our goal. That is to replace all SN5 in the world with our SN to make them easier.