We use 4 different styles of Tee Terminal.
We have found that these are the most commonly used and cover most manufacturers of yacht masts.

T Terminal Flat Head This style has the wire diameter embossed into the flat side of the Tee. Commonly referred to as a Hasselfors Tee Terminal

Tee Terminal Spoon Type These T Terminals are referred to as Gibb Spoons. The wire size can be found stamped into the underside of the head.