This does not affect your right to an exchange or refund for faulty equipment.
The two way locking spindle in the shackle allows connection to fixed loops such as wire strops, rigging plates, & harness bridges. The fixed eye can be clipped (with a Prest-in configuration aid if needed), spliced in, swaged in, etc. as required.
The small D shaped shackle keeps single attachments neat & predictable whereas the increased size of the bow-shaped shackle allows complex set ups to be achieved by catering for loading across the shackle.