A Northern Polytunnel Hoop is made from 4 Pieces:

A Greenhouse Leg, a Half Hoop Plain, a Half Hoop Swaged and a second Greenhouse Leg.

These are all sold separately as listed 

18ft - 21ft Hoops

Made from 50.8mm diameter tube with 1.5mm wall thickness with 1m straight sides.

24ft - 30ft Hoops

Made from 60.3mm diameter tube with 1.5mm wall thickness with 1.07m straight sides.

Greenhouse Legs

For 50mm hoop:

18ft - GFT507 GREENHOUSE LEG 50.8MM OD 700MM LONG

21ft - GFT507 GREENHOUSE LEG 50.8MM OD 700MM LONG 

For 60mm hoop: 

24ft - GFT607 GREENHOUSE LEG 60.3MM OD 700MM LONG

27ft - GFT607 GREENHOUSE LEG 60.3MM OD 700MM LONG – £8.70 – No VAT 

30ft - GFT607 GREENHOUSE LEG 60.3MM OD 700MM LONG - £8.70 – No VAT