Lunge lines are made of synthetic material or cotton rope. At one end they have a swivelling snap hook that is hooked into the horse's bridle. At the other end there is usually a hand loop. Simple models are just under eight metres long, double lunges have a length of about 16 metres. A cotton rope lunge line is usually lighter than the synthetic version. However, in rain or other contact with moisture, the material quickly becomes saturated and then very heavy.
This is not an issue with synthetic lunge lines. Lines made of nylon webbing provide easy grip. However, you should still wear gloves. If you want to pull the lunge line through the snaffle rings, a rope version is better. With all models you must pay attention to good workmanship. After all, the line and hook are subject to considerable forces.