Cardarine and SR9009 are PPAR up regulators. Cardarine/SR9009 increases the expression of genes involved in the expenditure of energy, stimulates glucose uptake in skeletal muscle tissue and burns fat by stimulating fatty acid oxidation.
Yes - both will burn body fat when in a caloric surplus but the most efficient way to burn body fat is in a caloric deficit. When bulking, you always put on a little bit of body fat so by adding cardarine into the mix, you probably won't gain any body fat.
It's kind of like - cardarine looses body fat + bulking gains body fat = no net fat gain
The nicest thing about cardarine and sr9009 is that they are not stimulants or hormones so they won't effect sleep, raise cortisol levels or anything like that. It'll cause a huge boost in fat loss with no side effects.