Saw one of these discussed and got it for my RFM. Converts 1v video signal to 5v to improve display on the CRT. Costs 22 plus $31 and arrived in 3 days.
Mine was very easy to install, and does make all the graphic very sharp, showing detail I didn't know was there eg you can see the stripes on the ropes on the leaning tower of Pisa. Didn't need to do the 5v power addition some have to do, and made my own connecter courtesy of $5 components from Jaycar.
Worth it for Pinball 2000 owners.