Trying to pass images to shell command using automator

I am creating this service for Finder that will receive image files and pass to a shell command. The idea is this: 1. I select image files on finder. 2. I right click and choose the service I am creating 3. the service receives the files and passes to sips, so it will scale the images to a given size. this is how I created it. sips would run on terminal if I type sips -z 750 1334 *.png (or any other extension, including *.*) I am hoping that $* would pass a list of arguments to sips, but this is not working. How do I do that?