Terrific to find reasonably priced used equipment to support our entry-level hobby. Our Nikon D3500 kit didn't include a speedlight back in 2018, and now its obsolete. It is our 1st ever and only dSLR. So, off to eBay, bought an SB-800 flash. Didn't know about MPB until we couldn't find an SD-8A external powerpack for the flash. Google Search found it on MPB, signed-up, bought the powerpack, got it, tried it and find it works as expected with six (6) AA's. Expect those batteries to be replaced awful fast at today's prices. So, replaced four (4) AA's with low cost 9/16-18 bolts cut to size, and replaced the last two (2) AA's with two (2) 14500 rechargeable lithium batteries. The powerpack works like a charm with the flash. Two (2) rechargeable batteries in the powerpack and four (4) backup lithiums will last a whole lot longer than those AA's. Thanks to MPB for being there. Next, we need a 16-80mm f/2.8 VR lens for a wedding that we got volunteered to shoot next June. Knowing MPB will come through again. Thought about the 18-300mm f/4.5-5.6 or 6.3 lens, but cameradecision and pcmag don't like it as much as the 16-80mm lens. Go with the pros we say, like MPB.