It has both omega 3 - from linseed and omega 6 - from soya oils, plus probotics and various vits and mins as I understand it.
I feed mine for a lot less of the cost compared to Outshine which is £33 for a 20 k bag.
I buy 50 k of linseed (£23 for 25 k sack) and 25 k (£40) sack of brewers yeast at a time which with delivery is £108 from Charnwood. I also feed black sunflower seeds - high in omega 6 which I pay £20 for 20k from my local feed merchant.
This combination gives me omega 3 and 6 oil, probiotic and also is great for helping my horses SI. If I also need a bit more weight, I can choose to up just the linseed element.
Finally I feed fibre products rather than cereal products and Outshine has wheat in it.
However, I do take time mixing up my various bits and bobs and to use Outshine would take less time.
Linseed is omega 3, this is why I also like to feed the BSS for omega 6, plus the BSS help to give very hard feet and a dark coat.
What are you wanting to achieve? As well as having glossy coats etc for the show ring, I also feed linseed as it is excellent for joint health, digestion and as I feed only forage products, compliments this way of feeding.
As you say many folks just feed linseed, I feed the other stuff for SI and foot health.