This INTRAFUSE® STEN magazine loader will save you time and frustration. Quickly and easily load your magazines with this simple to use sleeve-style loader. Depress the loader with one hand and position the next cartridge with the other. The textured surface provides a non-slip gripping surface to help keep things steady. There are no more parts to break, lubricate, or maintain. This handy tool also features a small opening for attaching a key chain or cord for storage.
Cheap compared to what I paid. Only $10 from this site:
http://www.tapco.com/products/index.php?_a=viewProd&productId=288