Used to shut unused One-touch fittings , Lightweight , Variety of sizes to fit all KQ2 fittings, FITTING, PLUG, CONNECTORS, KQ2 FITTING, JP, KQ2 10MM, .00734 lb
KIT FLANGE MT NC*JP*15. ACTUATOR. 15MM NCJP ACCESSORY. .07705 lb. G2.
KIT, FOOT MT NC*JP*6. ACTUATOR. 6MM NCJP ACCESSORY. .01958 lb. C2.
In addition, you may refer to the “Specific Product Precautions” in the catalog as the part numbers are listed there as well. 
The VHK series catalog can be found here.
The VHK series catalog can be found here.
The VQ7-6/VQ7-8 series catalog can be found here.
Further details can be found here.
Though it depends on the usage, stopping for a few tens of seconds should not cause the stop position to shift much, but holding the position for a long period of time is not possible.
Video
X port:
This is the external pilot pressure supply port. If an external pilot type valve (semi-standard) is mounted, supply pilot air to this port at all times.
(Refer to the FAQ about switching failure, which can be found here.)
For normally closed use: Plug the B port and pipe to the A port.
For normally open use: Plug the A port and pipe to the B port.
Note) Do not plug the exhaust ports (EA or EB); instead, mount a silencer.
The new VT307 series catalog can be found here.
The new VT307 series catalog can be found here.
The VT307, VT317, and VT325 series catalogs can be found here.
The old VQZ series catalog can be found here.