I am new to using insulin and had to start because I have a diabetic cat who is on one of the insulin pens. In the beginning (before sharps container), I actually managed to stab myself while trying to put the cap back on the needle so I could remove it and the needle punctured the plastic cap. Not good.I was scared and needed a SAFE way to dispose of the needle caps. I happened to find this container. This container is AMAZING! No kidding, it really is. After the injection, you just place the pen tip (needly area) in the hole and twist the pen. It unscrews the needle tip from the pen, then you press a button and pull back the needle holder and it falls into the container. No accidental sticks. It looks tiny but it is holding A LOT of pen tips. I love that it is small and I stick it in my cat's 'diabetic bag' where I keep his glucose monitor and needle tips. I do want to say, in the beginning I did struggle a little bit getting the pen tip in the hole and thought it was useless. Just press it in. It will go, just press. It could be because I was nervous and didn't want to break anything, but over time that sharps container is like my best friend when insulin time comes.