Same as this chain ring (which IS 151 mm though), it is the "Record" type, which is good and nice.
It's not completely new, but it has just minimal wear signs. So, decades of life in it.
HarrieH's classic track bike project
A track bike has the beauty of simplicity. No distraction of cables, bottle holders, pumps and other accessories. Just a frame, fork, drivetrain, steering components and something to sit on will do the job on a track.
Some parts I already have for decades, others I have to collect. It's fun to look for the right components, to get them, build up the bike and, of course, ride it on the velodrome.
Oh, besides track, lots of (off-)road stuff as well.