The open center design of Lovejoy coupling spiders is suitable in close BE situations (distance between ends of driven and driving shafts), where units must be positioned as closely together as possible. However, this design has no full-diameter support, as the spider's legs are joined only by a thin segment of material. It has speed limitations up to 1750 rpm for NBR and 3600 rpm for Urethane / Hytrel. The solid center design of Lovejoy spiders is suitable for general power transmission applications where the BE dimension will remain fairly constant and will be capable of affording a suitable gap.