This is the most basic sewn eye. Webbing is just folded over and sewn and this type of eye is often used in a choker hitch configuration.
Half twist eyes offer two advantages over the standard flat eye:
There are times when the webbing is too wide to interface with another component. The webbing in the eye can be folded in half and then sewn. Then we sew the actual eye. This treatment is frequently used with large lifting slings (which we do not make) but there are plenty of applications where a flat tapered eye is the right choice.
The flat and half twist eye use the same amount of material, the flat tapered eye just a bit more. Labor wise the flat eye is the fastest to make, the half twist version takes a few seconds more but the tapered eye introduces another operation, folding and sewing the webbing, that is done on a different machine prior to sewing the actual eye. There is about three times the labor in a flat tapered eye as compared to the plain flat eye.