The little ones are block/bleed valves , fitted to instruments such as pressure gauges so you can isolate the process, vent between the instruments and the valve and then remove the instrument. The bigger ones are manifold valves, similar thing for instruments with two process connections. Well worth £10 if you have a use. Probably rated for quite high pressure.
The manifold ones are for use on differential pressure instruments. The red is the process line tappings, green the equality zing valves, yellow the bleeds.
They will be rated to either 6k or 10k...psi....and are about 300 quid each