Selden Original Spreader Bottlescrew Adjusters 503-766-01. Bottlescrew adjusters come as a pair. For over 15 years Selden spars have been supplied with turnbuckle or bottlescrew spreader adjusters, and spares for this system will be available for the next few years. This system has been replaced on new spars by Seldens latest system, Seldens continuous development program provides the additional benefit of simplicity, built in dihedral and lightweight.