The model 25 and model 13 are VERY similar in design. Just like the 125 and the 115 are similar in design.
The 125 and 115 may LOOK way different, but if you look closely you can see they are very similar. The doors just have a different design. Like if you make the 115 housing bigger, but keeping the curves the same, it would look just like the 125. Also if the 115's door design was different, with it more flat with just that one slant back, you would see that the 115 would just be a smaller version of the 125.
Not to mention the photocell socket position is different and the 115 has the heatsinks and screw holes on top. Other than that the two top housings are pretty similar. The M-400R2 looks like a bigger version of the M-250R1
The 125 and 115 may LOOK way different, but if you look closely you can see they are very similar. The doors just have a different design. Like if you make the 115 housing bigger, but keeping the curves the same, it would look just like the 125. Also if the 115's door design was different, with it more flat with just that one slant back, you would see that the 115 would just be a smaller version of the 125.