How safe are these? Has anyone used one like this that has space at the tip on the inside for when you ejaculate? I have over but it seems it creates too much vacuum when using it so i stopped. If your scroll through the pictures you'll see what i mean about the space at the top.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F33 2836541758