Do you mean 49cc 2 stroke???...What engine in particular do you actually have as this will make a difference of what size your clips are gonna be...It is gonna be either a 10mm or 12mm clip and I see that, that kit starts at 11mm, not 10mm.
My engines are both 12mm because they are Phantom 85s so take a minute or two to tell us what you got so we can tell you what fits...No different than going to an autoparts store for your car parts, a Ford part doesn't fit a Chevy product.