They are NOT related to either OPN or Siya as those are based on the Velox platform (Oticon’s newest platform). They are new to NHS and are an upgrade/update on the commonly prescribed Synergy Spirit, but are based upon the newer Inium Sense platform.
The reason your aids look different is that your area has decided to prescribe the “mini” BTE hearing aids. I have noticed a growing trend appearing that more and more areas are moving slowly to these mini-BTE packaged aids despite the fact they cost a little more to run due to using smaller size 312 batteries. I hear this is because acceptance ratings are better.
As I understand things various Oticon favouring areas will probably be slowly moving towards the Synergy Sense aid over the next year or two. But not all can quickly do so as programming it is different and that means kit, spares, software, training etc.
For what its worth my experience of Synergy Sense has been good. However my prescription is a very unusual one and my aids, whilst part of that family, are also an unusual variant.
I have the spec sheets for all the variants somewhere but as I recall all have decent bandwidth, 16 channels, quite a lot of decent software features and are IP58 water-resistant.
Hope that helps