hello in response to your question i have a 16.2 who is very cheeky, he was 6yrs old when i got him and he'd had no schooling he was a nightmare it took three people just to lunge him in the end i waited till it was quite and went into the school on my own with him he kept running in so i tapped his shoulder with the lunge whip after a while he got the idea i just kept nagging him now he lunges fine.there no hopes of getting lines on him so i had no choice