 The hints and tips that I would want to give you tonight, with regards to the actual materials that you're going to use in your structure, it would be the following, I mean, if I was going to renovate, I would make sure that I use a reputable supplier. So wherever I'm going to buy my material from, I should know that I am able to go back to that supplier and confront him if something goes wrong. I think that's the most valuable point that you can, or the most valuable thing that you can do when renovating, make sure that it is a reputable supplier. Then secondly, with the materials that you are buying, when you renovate, not all of us are concrete specialists and not all of us go through all the tests that we go for grading analysis, relative tests, it is all of that when we have a look at materials. And rightfully so, I don't expect the viewers to do that. But ask that supplier to give you a track record. Ask him that this material that I am buying, where was it used, give me a track record and go and have a look, see if it structurally sound. It gives you a good idea of what the materials are that you are buying, especially if you don't know what's taking place. Then secondly, or thirdly, is used asking to give you a technical data sheet of that specific material that tells you exactly what that material is of, because that's what you're going to buy. And most probably you're going to buy it once or twice or three times, you're going to buy the same material, but you want that material that you buy to be constant. And you want to make sure that what you are buying is what you are getting. And you can always refer back to that technical data sheet. And even when you get your materials, take photos of it. Those are things that we can use afterwards to go and have a look and see what is it that you receive and what is wrong. And then another thing is visually. Everyone has that feeling inside you when you look at something. Make sure if you have a bad feeling about it, normally it's bad. Okay, there's something wrong. Okay, so when you have a look at the material that you're buying and looking at the aggregate site, for instance, make sure it's free from tweets. Make sure there's no seeds visually that you can see in there. Make sure that you don't see leaves in there. And then another thing, look at the color of the material that you're buying. Make sure that the color is uniform. I mean, if you see that there's huge color differences in the material that you're using, you know that you're not using a constant material. That material has quite a lot of variances in it. And another thing that, for instance, looking at your sand. If you see lumps in your building sand and there's big lumps, it tells us it has a PI. That material is binding. It means it has quite a high clay content in it. And I don't want to get into too technical sign of it, but that clay is going to shrink and going to cause problems all over your plot to work at building board. So make sure if there's lumps in it, ask the question, where was it used? Is it fine? And where does this lumps come from? Another thing that we can have a look at this visually is contamination of that product. And on your checklist, make sure that it's not contaminated. The bins where the materials are in that you're buying from. When you have your sand, your stone, your crust is sand, whatever it is at the end of the day, they shouldn't be contaminated by us first. You shouldn't buy a stone that's already contaminated with sand. I mean, later on when you're going to use the PPC calculator, it's going to tell you, you must use so much stone, you must use so much sand. But if it's contaminated material, the proportions that you're trying to mix is not going to be right. Because you have contaminated material before you've even started. That's the one thing. Then another thing that's vitally important is when you buy a bricks in a box, make sure that those bricks and blocks are tested. And it's vital. That's the backbone of your structure. Make sure that they are tested and that they conform to the minimum standard of the sand, one, two, one, five. You know, Ruan, one of the things that...