Trailer brake question-round magnet and oval magnet ?

Besides shape, what is the difference? Can round work where oval was used or oval where round was used? Are drums different for the different magnets? Thanks guys. My first go around with changing out brakes on the trailer.

 

I just get the numbers off the axle and buy direct replacement parts. Sometimes you can upgrade the brakes with a stronger magnet, but you have to cross the part numbers. You really can't go by looks.

 

I got this of an other website about trailer brakes
The ovals are more powerful, use them if you can & if they will fit into the drum

 

We used to sell these parts... and complete backing plates with brakes installed... We found that the surface area on both styles was about the same.... thus the same pull if they both started with the same resistance... its the amount of current through the coil that makes it attract to the drum.... BTW we'd turn the drum and also resurface that surface if it was damaged for the customers...