The smart glue ring cups is great little tool to make your extensions lift easier.
You can still wear it on your finger and it helps a lot on making perfect fans.
V breaches/grooves have different sizes at the fanning cup edges, which can wipe extra glue for volume lashes and keep the roots bonded into one cluster.
Deeper V grooves work for 6D-9D volume fans, and shallow one works for 3D-5D volumes
Rapid fanning cups could keep the glue from flowing out, extending the glue drying time and maintain good performance