Q&A's:
"does this product come with battery and battery charger"
Hi Phil, the product you picked here is aluminum ""Mounting Bracket"" only for a reciprocating saw, so the short answer is sorry no. If you want the saw it comes as a kit part number DCS380P1, DeWalt and yes that will come with a battery, and fast charger.
"how big is it, and how heavy?"
The brackets weight is 0.85lbs. It is designed to hold a multiple sizes of reciprocating saws.
"Does it come with charger? What kind of Battery? Does come with any blades?"
This product is just the holder. The saw is sold separately.