The 12ft (3.66m) Wide Polytunnel With Sliding Doors At Each End Has 3ft 3in (0.99m) High Straight Sides And An Overall Height Of 7ft 7in (2.31m) And Provides Good Air Circulation And Ample Growing Space For The Seasoned Gardener. there Are Two Designs Available; Trench Or Rail Versions. With The Trench Version You Will Need To Dig A Trench Around The Perimeter Of The Polytunnel To Secure The Structure Into Place. The Rail Version Doesnt Require A A Trench And Is Supplied With Anchor Plates To Secure The Polytunnel. Although The Trench Version Is Slightly Cheaper, The Base Rail Version Is A Stronger Alternative Which Is Easier To Install.the Film Covering Has Been Specifically Designed For The Uk Where Low Light Levels Are Common Allowing 90% Light Transmission Allowing Through More Of The Light Spectrum Used By Plants. It Also Scatters Light Entering The Polytunnel. This Uv Stabilised Film Is 200 Microns (800 Gauge) And Is Supplied With A Five Year Guarantee.timber Sliding Doors Are Supplied For Each End Of The Polytunnel, Anti Hot Spot Tape And Of Course The Framework To Support The 200 Micron Smart Clear Polythene Cover. a Polytunnel Is A Cost Effective Alternative Or Addition To A Greenhouse And A Warm Covered Plot Will Certainly Extend Your Growing Season And Increase The Number Of Different Varieties Of Vegetables You Can Grow.12ft Polytunnel With Sliding Doors (one At Each End)sliding Doors Increases The Available Growing Area Inside The Polytunnelavailable In Two Options - Trench Or Rail (supplied With Anchor Plates)covered In Uv Stabilised 200 Microns Film (800 Gauge)width 12ft (3.66m) Hoop Spacing 5ft (1.53m)3 Lengths - 15ft (4.57m), 20ft (6.10m) 25ft (7.62m)overall Height 7ft 7in (2.31m)straight Side 3ft 3in (0.99m)head Room (15cm From Side) 4ft 8in (1.42m)hoop Diameter 1in (25.4mm)steel Specification Z35 Galv High Tensiledoor Opening Width 2ft 3in (0.69m)door Opening Height 6ft (1.83m)distance Over Hoop 22ft 8ins (6.