1/4" UNF Nyloc Nut. Quarter inch diameter nylon insert lock nut. Unified Fine Thread.
||Locking nut with nylon insert to prevent loosening
||Using the correct size is vital
||Zinc Plated for corrosion resistance
||'Cream' plastic insert meaning Imperial size nut.
||Standard depth or number of threads
NOTE: It is vital to use the same size and depth of nut as originally fitted to your hang glider.
Using the wrong nut courts disaster. So check the nut you remove carefully and make certain that you order the same size and thickness replacement.
The quarter inch UNF is quite a popular nut size on many hang gliders. (However this is not a thin nut which is also available.)