I felt uncomfortable placing 12 inch kayaks on my Kia Soul's factory roof racks. I used 1-3/8" (35mm) chain link railings to build a large platform on top of my car to attach my kayaks to. The 1-3/8" fasteners are at the large Orange Box Store not available, probably due to low demand for such an item. However, it was the right size, material and price (stainless steel for less than $1 each.) They are THIN I got them due to the trouble in folded down the middle, bought 6mm screws for easy assembly and am very happy with the result.