I have also bought the costume for my 8 year old son. It is indicated with size 134-140 (7-9 years). My son is now 128 cm tall and I would say that it turns out to fit. Next year it will probably no longer fit. Now for Quality: very thin fabric quality. The first time wearing the poorly stitched seams on the zip have above and resolved down so that the zipper is gone out. With a lot of patience and time for sewing, it is now back to normal.
Conclusion: Although the costume was inexpensive (I paid 16,49) But we must just do not expect quality at the price. I think I would buy it not again.