Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Does this Tamper have a flat or curved base
Document: very nice tamper good weight, handle lets you get a  good grip and is comfortable, also fits lm ridgeless style double and triple baskets well. my 1st flat base tamper works great, less channeling issues than my previous one. A+
This Rattleware Tamper is excellent. Having used tampers ranging from the plastic one that comes with the Espresso Machine to pressurized tampers costing $100, id have to say that this performs just as well for a fraction of the price. Definitely the best bang-for-your-buck tamper that I've used. Very sturdy, solid feeling. And as for my fear of the base being jagged or having a seam - the base is so flat and polished that i can see my reflection in it!
No more grounds overflowing at the sides. My tamps immediately improved a lot with the new tamper. The sides of the basket are almost perfectly clean after a single tamp and it's far easier to get an even and straight tamp.You could spend a lot more money on getting a tamper with some exotic hardwood handle, but as far doing the job it's intended for, I'm sure this product does just as well as any of the models that cost many times as much.Note that this tamper has a flat base.
This Rattleware tamper is as good as it gets. It fits my hand comfortably, is the right size and looks good also. I like the flat bottom a lot better than some other tampers which have curved bottoms. I have not found a better tamper for the price. [..]
As a shop mechanic trained and certified in Switzerland, I can give an expert opinion on the build quality of this product. I am a novice when it comes to espresso making.I was truly impressed when I took this tamper out of the box. It comes in a plain cardboard box and is protected from scratches with a thin cloth bag. I think the bag is meant for transportation only.The tamper itself has a stainless steel base topped with a plastic knob.
I have had $40 tampers and have been making espresso with pro-sumer machines and 58mm porta-filters for over 20 years. There is nothing lacking for me in this tamper. If you feel you need a solid SS or rosewood handle tamper; you, of course, will pay another $10 to $40 for those. Me, I just want a SS tamper with heft, and a nice flat, polished, tamping surface. This one works for me!
I purchased this tamper to use with my Rancilio Silva. The bottom of this tamper is flat and will not allow me to apply pressure to the ground coffee beyond the ridge in my Rancillo basket. Gives a nice flat (loose) tamp, but I still need to use my originally supplied plastic tamper to properly tamp the coffee at 30 lbs. Don't know if there's a convex bottom version of this tamper?? If so, I should have purchased that!
How hard can it be to make a good tamper? At a reasonable price, apparently pretty darn hard. I think this tamper is a good compromise between really expensive brands and the questionable cheap brands. The quality on this piece is great...it appears to be a solid piece of machined aluminum with a rubber cap for added comfort. The tamper fits the portafilter on my silvia well. There is no flex, the flat tamping surface is smooth and grinds don't stick to it much.
The rest of the visible steel is brushed. The size and logo are etched into the parallel part of the shaft. It is machined with high attention to detail. No edge is too sharp or too blunt.The plastic knob is threaded about an inch into the steel base. I don't know whether the manufacturer offers different knobs/handles or replacement parts, but the threading would allow for this. The threading is executed just as it should be.
I've not noticed any channeling issues with flat tamps, but then again, my experience is rather limited.
Answer: Flat