To fill you pull the plunger all the way out and fills with fat. But not completely, but about not fill the upper 2 cm. Then pump a few times, and the fat is coming down from the top.
The press is delivered in a cardboard box empty. Another nipple is in a bag in a box.
As fat I use Allround grease with lithium for Sbschmieren the rails. In my three Husqvarna models are available at the bar tip left and corresponding right holes. This prolongs the life of the rail.
The press is so compact so that they can have in their belts while in the forest readily.