Refills are awesome for several reasons.
1. They use about 70% less plastic than getting a new jar. HELLOOOO!
2. They have one extra gram of product in them. That's a lot.
3. They cost $2 less than the jar.
Refills are available for Foundation, Blush, Face Powders, and Concealers
I use a thin butter knife. It's thin enough to work under the edge of the sifter (which goes all the way out to the edge of the jar - I mention this because when it's put together it's hard to see that) but it's not sharp enough to cut me if I slip. (And I DO slip. 😬)
I work around the jar until the knife can get all the way under the edge of the sifter, then I continue to work around the jar, lifting and prying it a little bit at a time, and a little more until the sifter comes out.
Some sifters pop out easier than others. The whole process does get easier each time you do it. I'm not sure if the fit gets a little looser, or if experience makes you better at it. 😀
The powder in the refill won't really all fit in the jar at once, so don't try to dump it all in. It'll be a mess. Aim for getting about half to 2/3 of it in there. There will be more left for refilling later.