Where do you want to use it? The white one is meant for brick to brick insulation, while the yellowish/greyish is okay with metal to metal or metal to brick insulation. When you go to the market, refer to Rockwool or Kaowool. Those are n names commonly known and used.There are other safer and cleaner options depending on where to be used. If you give extra details,i can advice for the cost of two cold ones. Meanwhile, try with EA chains, Marshall-Fowlers or Nyumba ya Chuma if you are within Nairobi.

Rockwool/Kaowool will do then .We have other options such as silica slabs which are fairly light in weight and not as messy as the former, fire clay, which is fairly cheap.Others are Fondu/trimor refractory cement for inner walls which can be used with high temps metal fibres called Meltex. Unfortunately, Meltex is not locally available. Remember to seal tightly as this products are made of very fine fibre glass and are a health hazard when inhaled. Good luck.