Blue Label OC71?

[Guava13]

I recently came across a few OC71s. 2 of them are the normal white label, but the rest are a blue label. Has anybody here ever seen this? It doesn’t look like any kind of aging from what I can see, but I’m no expert. It was tough to get a good pic, but here’s one showing the normal white at the left and a couple of the blue ones to the right.

[The Captain]

Has anybody here ever seen this?

Yah, I've had Mullard OC75's that looked the same. I thought it was ageing at first but there was like 15 or so of em, and all quite uniform in colour too. No idea what it means, if anything. Sure looks cool though!

[Arcane]

I have some black glass devices with blue print. Looks neat.

[Guava13]

Ok very cool!