Logon Screen Application Icon - Size, depth ?

Hello All,

First time posting. I have a VPN client which create a pre-logon configuration. If I click the Network icon, I can select the VPN client to launch prior to logging into the domain joined machine.

My question is, the default vendor icon looks terrible. I've tried numerous size Icon files, but I cant seem to do the following;

1) make it higher quality (similar to the user account picture)
2) eliminate the Gray border around the Icon.

I've tried 64x64, 95, and 512.

Any help would be greatly appreciated.

Thank You