[makomk]

On paper, that means you don't have to join the union in order to get a job - just pay the union fees and work under the union contract (which is to say, almost all the downsides of joining but without any actual say in how the union is run). In practice, I think people who do this tend to get blacklisted by the union and have trouble getting jobs in future. I know the Hollywood unions in particular are very aggressive and public about threatening anyone who takes that option with blacklisting, and there are zero consequences for them for doing this.

[whimsicalism]

As a counterpoint, in my unionized school district, both options were quite popular and you didn't need to pay the full dues, only like 70%.