Anyone using the LubeLocker Gasket?

I’ve got front and rear diff lube lockers in my shop waiting for when I open the diffs next.

i have one on mi 42RLE transmission pan right now. It’s been on since September/October time frame. Worked well with no leaks.

I also have a trans pan lube locker for my Silverado for when ever I get around to that fluid/filter change.
 
I’ve run Lube lockers on all my diffs. 30, two 44’s and a 60. I’ve not had any leakage or seepage issues.