This little thing is handy! I bought it because honestly, I am done packing wheel bearings by hand. I own a Datsun - a few, actually. Wheel bearings are kind of general maintenance with the way they are driven these days. And it's a pain in the butt, you're going to get dirty, you're likely going to get grease everywhere, and it just becomes a mess. Plus, even if you wear gloves, generally the wheel bearing will rip right through them (Even the black venom gloves) if you're not careful. I'd rather not mess with it. I'd rather take a bearing, blow it clean with solvent and air, inspect it, throw it in this little device and push until my anger and frustrations have flows through me. Boom, done. Bearings packed, no more scrape-scrape-scrape-wipe. Give a good 'bath' in some grease on your finger, preload your hub with a bit of grease, and reinstall your bearing. It's that easy. I give this 4/5 stars because I think it can be better. 1.) The product is great, and very sturdy - but if you aren't pressing straight down, some grease will go past the O-rings on the plunger. This means less pressure for the grease to pack the bearing with, and, it allows grease on the inside surface of the tube. Which means you're going to get grease on the dust cap (red). I think using a slightly thicker housing, with a double (or triple) O-Ring seal for stability and extra protection, and you'll have a champ. 2.) Cleanup can be hard, and you're going ot be limited to using a rag/paper towel and just dry wiping until you're satisfied. With this, you'll eventually have a dust build up (nowhere near where your bearings will pack, but in the housing itself). 3.) The threaded portion kind of threw me off because even with a relatively small bearing (Timken SET2 or SET6), the threads don't engage. So I was trying to thread the piece on and it's just not happenin'. Because it can't. Not sure the purpose of this. 4.) This device has a grease zerk, for a reason I honestly couldn't tell you. I'll never use it, you'll probably never use, but it's there. 5.) The dust cap should also cover the entire unit, not just slip inside the housing. It's a harder plastic, too. I think a larger, rubberized plastic would be nice. 6.) It doesn't clean my wheel bearings, too. Things to think about: If you're buying this because on occasion you want to grease some bearings (duh?) but you have multiple greases you plan to use (I use Valvoline Synthetic generally, but I also use Redline CV-2 and Amsoil Polymeric/Polymeric 5% Moly) then you're going to NOT want to cross contaminate your grease load. Just bite the bullet and buy a second or third packer for each grease you plan to use. In the case of wheel bearings, you'll likely only use one. Maybe a marine grease if you have a boat trailer, or maybe something else. I dunno. One 10oz tub of Redline CV-2 grease fits PERFECTLY in this. Let's see. OH. If you have a thicker grease (Amsoil Polymerics come to mind) then it will take longer to pack a bearing. You're going to go through a lot of muscle - I could literally stand on this unit with CV-2, and it still took a moment to pack the bearing. Food for thought, this unit may be a little pesky if you live up North. Thinner greases are no problem at all (Conoco Red, etc.) I plan to keep this entire thing in a zip-lock bag. One, to keep the grease smell out of the air. Two, to minimize dust contamination. 3.) Because I don't want water to get into my bearing packer.