The model is a 686. There will be a - and another number. That is an engineering revision, not part of the model number.
It is the product code that defines a specific configuration. It is most likely the revolver pictured is product code 104225
If you have the factory box, that information will be on the end label.
As to features, your revolver has what is called a full lug barrel. The adjustable front sight was introduced for silhouette shooting. It allows the revolver to be sighted in at all 4 different distances or if you are not a silhouette shooter with different ammunition. Just rotate the dial and your sight is changed to a different preset