Set of four, regulation flyball hurdles, crafted from a special, warp-resistant fiberboard. We use the quick-change design preferred by competitors, since it allows rapid change in heights between runs. Boards can be slid through the uprights from either side. No tools or hardware required for set-up or tear-down. Each hurdle comes with 6" bottom board plus 4", 2" and four 1" boards, allowing any height between 7" and 16" in 1" increments. We offer a pack of additional 1" boards if you need replacements in the future.