Yep this is my favorite boil and bite. I don't know how they compare to custom fitted ones but they have worked great for my sparring. Best part about them is they don't cut up your mouth from being too hard. I tried like 5 other boil and bites with various problems, none of those here.

http://www.amazon.com/gp/product/B00BFID530/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Edit: These look like a similar design for another option http://www.amazon.com/Venum-Challenger-Mouthguard-Red-Devi/dp/B00F2U1CTQ/ref=sr_1_7?s=sporting-goods&ie=UTF8&qid=1420390865&sr=1-7&keywords=mouthguard