About me:  I run my own automotive detailing business and have cleaned and detailed vehicles for over 10 years.  For the record, I am a big time Meguiars loyalist and use their products almost exclusively.  However, I was getting tired of spending $20+ dollars for the 200gram clay bar in their professional detailing line up and furthermore, I was tired of spending $17+ on the consumer lineup bars for either the Meguiars or the Mothers that come with the detailing spray to use as lubrication.  I don't need the detailing spray bottles about 90% of the time as I rarely use them since I favor buying the professional lineup bottles in bulk as they are more economical.About the clay:  This is by far my favorite clay of choice.  Not even because it's cheaper, if it was more I would still probably buy it.  Maybe I shouldn't have said that in case the manufacturer is reading their amazon reviews.  Here's why:  The clay is always more firm.  The mothers and meguiars brand clay (aside from Meguiars professional) is always smushy, soft and very flexible.  So flexible that it becomes a pain to use seeing as paint contamination removal works in large part by friction and that friction relies on pressure.  The consumer line up of Meguiars and Mothers literally squeezes out of the sides of your hands with minimal pressure applied.  This brand stays rigid and allows you to apply more uniform pressure to the surface thus taking down the contamination quicker.This clay will NOT harm the surface of your vehicle much like the other brands that I have used UNLESS, used improperly with too little lubricant.  Make sure you give your vehicle a complete and thorough wash prior to using any clay bar on your vehicle.  If you drop the clay, THROW IT OUT.  Do NOT think you can salvage some of it.  I always start with the body panels that have the least amount of contamination on them FIRST and the heaviest contaminated surfaces I save for LAST, just like you should during a wash.  If you are not sure run your hand over the entire surface with a plastic bag on your hand and you will be able to feel what's what.  Try this test again when you think you are finished.  When finished, your vehicle will most likely be free of harmful contaminants and as smooth as silk.  I always clay vehicles prior to buffing and always follow up buffing with a good machine applied/hand removed waxing.Packaging:  Could be better as it arrives in a plastic bag that tends to stick to the clay and is taped shut making opening a pain.  Should package it in a container.  (I know this part doesn't fit into the review portion to some, but I figured it'd be worth mentioning). It doesn't effect my review by any means, obviously, as I rated this product it's deserving rating of 5 stars.Final notes:  If you are only claying a vehicle every so often it might be worth your time to pick up the Meguiars or Mothers kit.  They even sell them at wally world, usually cheaper than your auto parts stores.  Reason being is, it comes with the detailing spray/lubricant and a microfiber towel.  But, if you clay often and want IMO the best clay bar for the buck then I highly recommend going this route instead.Make sure to use plenty of lubricant.  I beg to differ with some of the reviewers comments about usage such as "wash one panel with soapy water at a time"... Why one panel at a time? Why not wash the entire vehicle at once first, from top to bottom?  Why "soapy water"?  We should be using automotive car shampoo.  "You can use one bar on a grimy vehicle several times over"... Personally I wouldn't encourage this process. If someone has a severely contaminated vehicle and they use this bar it should go in the trash after usage, in my opinion.  +1 to the make sure you fold/turn/flatten comments often during usage.  Spray a little detail spray on your windshield or rear window and press the bar flat into it with moderate pressure. Manipulate/stretch the bar a little when necessary.