The QT is a brush wiper sized for a quart size paint can. It snaps onto the pail by pressing the narrow end against the rim and pushing the top surface forward using both thumbs. To remove, lift up on the outside lever. This version differs a bit from the original RimTrim with the addition of the deflection on the top outside which makes it easier to hang on to when removing it.

Here's a video of the original (gallon size) RimTrim being installed and removed: https://www.youtube.com/shorts/zqYF1Wdv1zA