Harbor frieght coupons will have the limits printed on them. Most of them will say limit 6 per coupon or limit one read the coupon. As far as how many you can use per visit. they dont care about that. I went in with the flyer one week and baught 10 different things all with a coupon and 2 of them were for the free items they were giving away that week. The only thing you cant do there is use a item coupon and a 25% off one on the same item.