Here you go. The difference between the Gossen Tele attachment and the Profi Spot attachment.
The Lunasix-F on the left is the version that can also do flash metering and is wearing the 15/7.5 degree Tele attachment. This requires no electrical contact with the meter. The Lunasix-F meter cannot use any Gossen attachment that requires electrical connections via the 3 sockets at the top of the meter which look like 3.5mm stereo jacks.
The Profisix, (Luna Pro SBC), on the right is wearing the Profispot attachment which has adjustable angle of acceptance of 1, 5 or 10 degrees. This meter can also use the Tele attachment on the left. The Profispot attachment has what look like 3 x 3.5mm prongs underneath it which connect into the top of the meter.
These two meters with their attachments differ by about 1/3 stop which is probably not too bad considering their differing acceptance angles. I did quite a bit of testing using 7.5 degrees on the Tele and either 5 or 10 degrees on the Profispot. Both meters are very sensitive with regards to aiming the at the scene to be metered. You have to be very careful when metering.
One thing which drives me nuts with both these meters is the tiny ISO/ASA scale for setting film speed. The graduations are very fine and it is not easy to set the film speed exactly. (And I have just gotten a new pair of reading glasses). Ah well, what's 1/3 stop between friends, (or meters), when you're shooting black and white or colour neg.