New kegs, weird pressure release valves

[Hegh]

I have some new kegs that have some pressure release valves that I can't figure out how to operate. Does anyone else know how to use these?

 

[Hegh]

I think I just figured it out while purchasing other kegging supplies:

http://www.midwestsupplies.com/pin-lock-depressurizer-plastic.html

 

[tlarham]

I think I just figured it out while purchasing other kegging supplies:

I think that those actually go over the "gas in" post to depressurize. The relief valve you posted can't be purged. This is the style on all 19 of my kegs -- pin lock. To depressurize, I use a bamboo skewer or a small screwdriver and press the poppet.