SGT KNOTS Sonic Tipped Boot Laces are the perfect heavy-duty replacement lace for hiking boots, work boots, combat boots, and more! Our patented sonic tip technology presses and heats the lace material at both ends to form durable, fray-proof tips. Sonic tip laces last much longer under rigourous use than standard lace tips. Perfect for rugged outdoor activities, such as construction, hiking, camping, mountain climbing, and hunting. We also offer bulk shipping in 100 foot spools, if you want to create custom lengths. Note: Bulk spools do not come pre-made with ultra-heated sonic tips, you must cut your desired length and then melt the ends together with a lighter or torch.