I'm not an expert on chins but I think the diff, between 42 and 415 is size more or less you can google it and find the sizes are just a little diffreent.
these do not have o-ring seals so oil the snot out of them or boil in a grease and gear oil mix for long life. This will get you kicked out of the kitchen and your girlfriend will beat you so I warned ya.
I have a couple of extra 415 master links if someone needs one PM me with your mailing address after you get it find a replacement and send me it for payment of the one I'll send you sound fair?!