There are some machines that require an MEI VN-2502 with the VFM "snack" style bezel, because of a smaller validator opening on the front of the machine.  If you have a machine with the hole size handicap, you have to stick with the VN-2502, or an equivalent.  However, on many machines, especially newer ones, the hole on the front of the machine is a full 3" x 4" rectangle.  With that hole size, you can put any type of validator bezel style in it that you want.  People get confused over this a lot, because companies like AP sent VN-2502 validators out in there 110/LCM/120 machines, as well as other models, even though they didn't need that model of validator to make it fit.  Unless vendors know the model number keys by heart, then they are unsure of what validator can replace a VN-2502, so they replace all their 2502s with more 2502s, just to make sure they don't run into compatibility issues.  

Great news though!  If you have the 3" x 4" hole on the machine for the validator, then an MEI VN-2512 will replace the VN-2502 you currently have in there.  The VN-2512 has flashing lights on the bezel, and a larger area for a more attractive yellow sticker advertising bill denominations accepted.  It has been proven repeatedly that validators with higher visibility bezels, or attractive light displays, attract more customers to notice or buy from the machine.  The VN-2512 costs the same as the VN-2502 from us, and most other companies.  It's amazing that just by buying a slightly different validator bezel style can increase sales, but it really works, and you have nothing to lose by doing it, and everything to gain!  Pictured below is the 

VN-2502 (VT167) bill validator,

and the...

VN-2512 (VT166) bill validator.