Rattler Rope Racer Calf String Cowpokes Work & Western NEW! Rattler Ropes Striker Calf Rope Rattler Ropes Deluxe Calf Roping Practice Head Green RATTLER ROPES J&R Tack & Feed CO. The first four strand calf rope with a core, the Striker is the most consistent calf rope avaliable. It is constructed of a special synthetic, industrial strength polyester that will not stretch, giving it a longer life and more consistency. The four strands give the Striker a smoother, faster feel than a polygrass. The core stabilizes the Striker, allowing it to rebound to its natural state. SIZE: Left 10, Left 10. 5, Right 10. 0, Right 10. 25, Right 10. 5, Right 10. 75, Right 9. 0, Right 9. 5