This Silver 721D overlocker machine is a lightweight machine and easy to thread. This 3 or 4 thread machine has a built-in tension adjusting device, as well as a detachable extension plate for free arm sewing.  It has a variable stitch width of between 2.3 and 7.00mm, with an automatic safety switch which is activated when the looper cover is opened. Colour-coded thread paths and a self-threading lower looper for quick threading. All you need to do is lay the thread into the guide, press the lower switch and the lower looper will be threaded.