The No 300EC end cap is available in 12 common sizes from 4 in through 20 in diameter pipe.
M&M End Cap, Series: 300EC, Accessory Type: End Cap, 7 in
https://externalassets.unilogcorp.com/ASSETS/DOCUMENTS/ITEMS/EN/MM_Manufacturing_300EC10_Specification_Sheet.pdf- No 300EC end caps are shipped loose
The No 300EC end cap is available in 12 common sizes from 4 in through 20 in diameter pipe.
M&M End Cap, Series: 300EC, Accessory Type: End Cap, 7 in