I must admit, as I seen a young fella using one, they do work.
Old school, I guess. I don't want to search around gadget's just to find my zippo. In all reality there is no reason to split the pelvis bone or carry a saw to cut the sternum. IMO, You just need a good ol' solid, sharp huntin knife w/a 5" or 6" blade. Just cut a patch of hair off surrounding the a-hole then just stick your knife all the in on the outside of the rectum an make a complete circle, just follow the bone.
Standing over the deer facing toward the back of the deer, stablizing the front legs with yours, stick the knife in rolling up under the sternum and with about 3 or 4 good solid jerks should put you thru the sternum. Slit the belly on down, reach in an cut the wind pipe, grab it and roll it all out. You may have to do a little cutting on the outer lining as your pulling, depends on the size. Should be good an clean.