Safety Thimble: Uses Less Connection Points with a Bow Shackle. One of the most impressive features of the Safety Thimble is the shape of the “eyelet” in the thimble. This purposely designed eyelet was originally designed for use with 3/4″ Bow Shackles (usually misnamed as D-Rings, but can also be referred as an Anchor Shackle). … Continue reading Safety Thimble: Uses Less Connection Points with a Bow Shackle than the Competitors