The D-ID 540-S and D-ID 541-A Indexer is for sewing multiple single needle double chainstitch keyhole shaped and round end buttonholes with short tail thread trims on denim fly fronts. The indexer unit ensures buttonholes are sewn automatically one after another at required lengths and pre-set distances from one another. Distance between each buttonhole can be set seperately by the operator on the touch screen display. Improved thread catching structure of the head avoids thread fall off. Special processing of gears and cams on the head leads to a significant reduction of noise and vibration levels by a scientifically tested 8-10 dB. This greatly improves the operator comfort and efficiency.