They are not necessarily bad products, but be aware that when you buy Coolermaster, you're paying for a name. You will almost always find a competitor (e.g. Rosewill, Enermax, NZXT, Xigmatek) offering similar products often for a substantially lower price. Note that on some of the absolutely cheapest, you may give up 1C-3C of performance, but the difference won't be worth the money you'll save. If you are going for extreme overclocks, you'll want a better class of product, such as Noctua or Phanteks, for which you'll pay at least twice as much anyway.
Make sure your motherboard is suitable for whatever level of overclocking you intend. If it does not have heatsinks on its VRMs, I would not recommend any more than minimal overclocking.