Yeah... I know... I could've rolled-my-own, and usually I do. But, I had a $20.00 coupon with DX Expensive-neering, so this was a nice chance to use it, and I had only one more week left to do so. I also went with their experience in the toroid core type and turn windings. I'm really not that experienced upon determining core type make-ups and have only wound toroids a few times. The 1st time was with Fearless Fred's help upon homebrewing a MW 7 Element Chebychev LPF. That was over 25 years ago, and I still have that, which has three self-wound toroid transformers. Anyway... I went the lazy way, but am still glad that I've looked inside that Balun. Maybe, I've bought one that was built on a Friday? Hmmmmmmm???