Hi, for me is working perfectly since 5 years ago (and I tried absolutely all). But in diabetes, every person is a world...
this sponge is easy to find in electronic devices or components (mainboards, boxes for laptops, or to protect some articles -glass-).
Look for a firm sponge... not hard because it press out adhesive... and not very soft because doesn´t press correctly to body... a medium, where you notice a light preasure (with time and use, it will dissapear).
Cut sponge with same size dexcom adhesive, and in middle, hole for transmitter. Height must be same transmitter (g4 or seven plus), and in middle inside, I put a small transparent film (removed from my fixumull tape) to avoid it was taped to transmitter. Then apply your tape, firm, avoid air inside... and after some hour it will be perfect and when you remove or change, you will see the adhesive stay perfectly -in fact, it´s very hard to remove after 2 weeks, I use an adhesive remover wipes)
Regards