21B507 up for sale is a heavy canvas bag used for a military application to store tools ans spare parts , this bag has a cylindrical shape that is 5 inches outer diameter x 10 inches long to top , the top folds in some and has a draw rope  to close it off for storage , this is covered under Tadiran comunications and Soltam systems part number B-260 and US army number 12576953 , also NSN 8105-01-300-9515 , we packed the one in the photos to show the full shape , these can be also stored flat until your ready to use it , comes loose as shown in the photos , these are brand new from USA GI surplus , see our store we add new items like this weekly , thank you RWK