The gap between a 1.8m leash and off-leash freedom is where most recall training falls apart. You cannot practise calling a dog back from distance if the dog has never been at distance. A long line closes that gap safely.
Round braided nylon, 8mm or 12mm diameter, in 5, 10, 15 and 30 metre lengths. Bolt snap at one end, no handle loop at the other so it will not snag on undergrowth. Rated for medium and large dogs.
Which length
5m for early recall work in a garden or quiet park. 10m is the one most people use most of the time and the length to buy first. 15m and 30m are for tracking and scent work, or advanced recall in open ground. Longer is not better. A 30m line in a busy park is a tangle waiting to happen.
How to work with it
Clip it to a harness, never a flat collar, so a sudden hit at the end of the line does not load the dog's neck. Let it drag while the dog explores, and step on it or gather it in when you call. If they come, they earn the reward. If they do not, you still have the line, so the dog never gets to practise ignoring you. That last part is the whole point.
Part of the Recall Kit, with the treat pouch and clicker that go with it.