Shires Adjustable Rope Halter Purple/Black. Shires Adjustable Rope Halter in Purple/Black. The Shires Adjustable Rope Halter is a lightweight and easy to use rope halter ideal for horses that can be difficult to lead. The Rope Halter gently tightens under pressure to offer more control and can help to encourage lightness when leading. The Rope Halter is easy to fit and fully adjustable to fit most head sizes. Halter should fit with a fingers width all around the head. Not recommended for use when tying a horse up.