Perhaps the most economical lifter of all, the fixed-length spreader can be built to virtually any length and designed to accommodate a variety of sling types, like wire rope or chain and at different sling angles, (depends on headroom). Spreader bar ends are offered in a "clevis" style, eliminating the need for shackles to connect slings or pendants. In larger load capacities, shackles can be very expensive, so the minor additional expense for the clevis style design is often offset by the 'don't need a shackle-savings'.  If you have shackles, you can use them — it's up to you!