This is a 4cc tube of Team Associated Stealth differential lube. Team Associated spent countless hours developing this diff lube for their Stealth Transmission. This silicone based diff lube is used on the 3/32" carbide diff balls that fit inside the main diff gear, and can be used in any ball differential.
Sadly the Stealth diff lube no longer comes in the tube that you see pictured. The updated version comes in a small round container with a flip top lid. The lube is exactly the same, but I will miss the precision of squeezing out small amounts from the old style tubes. Lube 5/5, Container 4/5 as I still like the tube better.