Lifting Strops Slings Simplex Single Thickness and Duplex Double Thickness. These are manufactured in the UK to BSEN 1492-1 2000 from 100% Polyester fibre. The Slings can be manufactured to any specified length. If you cannot see what you are looking for please contact us. All slings individually labelled stating sling number,material,length and date of manufacture. They are all tested, a test certificate will be supplied. Safety factor of 7:1. All manufacturing has been assessed to BS ISO 9001.