The Singer buttonhole attachment usually comes in a deep green plastic case and contains the black coloured attachment and all of the different sized drop in discs and a cover plate for your feed dogs. The standard one came with 5 discs and others could be purchased. It makes straight and keyhole buttonholes and is wonderful because every buttonhole you make is the same size and perfect! You can adjust the width and the length varies from 3/8" to 1 1/16". The buttonholer in the green box was made for any straight stitch machine and even fits my Janome. The one in the rosy/pink box was for slant stitch Singers (301, Touch and Sew). The older buttonholes have metal discs while the newer ones(after 1960 or so) were made of plastic. These old buttonholers can often be picked up for less than $10. My local thrift store sells them at $3! I use my ancient old buttonholer all the time because the built in one on my Janome will not handle large or thick buttons which I need for the bags I make.