This listing is for a Hy-Gain 10 meter resonator coil (Order # 253) that features 3/8"-24 threaded sockets at each end (see pics).
It was originally used with the Hy-Gain (#257) 60" aluminum fold-over mast which is featured at this eBay listing:
https://www.ebay.com/itm/256268707287
Have questions? Let me know...