Building a caterpillar greenhouse tunnel? We have great parts! - inside connection sleeves for 1-3/8" fence rail (other sizes available, check the information side of the site, Tube Fittings) - tubegrips (AKA snapclamps, etc) to attach the poly (32 mm for fence rail) - heat-saver greenhouse poly, durable and great to grow under! - repair tape The BEST is the wire straps (1-3/8" X 1-3/8") to attach a horizontal run of fence tube to your bows. Wire straps make a FAST, firm connection without drilling (and weakening) the arch.