Master Series Ass Vault Locking Anal Expander

The Master Series Ass Vault is a heavy metal anal plug with a mechanism inside: turn one key and its steel petals open, then lock them with a second key so the plug stays at that size until you choose to release it. It's built for experienced players into anal bondage and control games, not for anyone trying a plug for the first time.

How a locking anal expander works

Closed, the Ass Vault is a slim, tapered metal plug. At the base there are two keys. The flat circular key fits a rectangular opening and turns the internal screw: counter-clockwise opens the petals, clockwise closes them. The second key carries a gold locking pin. Once the petals are where you want them, you line up the keyholes with the flat key, push the gold pin all the way in, turn clockwise and pull the key out. Now the petals can't move until the pin is unlocked. That's the appeal for bondage play: the wearer can't shrink the plug and slip it out, and the partner holding the keys decides when it ends.

Size and weight

Overall length is 3.4 inches, with 2.8 inches insertable. The plug starts at 1.5 inches across when closed and opens to 2.2 inches at full expansion. The plug alone weighs 9.3 oz (264 g), which is a lot for its size. You'll feel that weight as a constant downward pull, and many people buy steel plugs for exactly that. If you've only used light silicone plugs, keep the first sessions short.

Using the metal anal plug safely

Lay both keys out where you can see them before you start, and agree who keeps them. Warm the steel under running water first and test it on your wrist. With the petals fully closed, use plenty of lube and slide the tapered tip in slowly. Expand a quarter turn at a time and check in after each turn. Only open it as far as feels good, never to the maximum just because you can. The slim neck and wide base keep it from travelling further inside. If anything hurts, unlock, close the petals fully and remove it. Never remove the plug with the petals open.

Lube and temperature play

Stainless steel is non-porous and works with every type of lube, so you can choose a long-lasting silicone formula, which suits a toy that stays in for a while. Steel also holds temperature. Warm water makes the first contact pleasant; a few minutes in cool water gives a crisp, chilly start for people who enjoy that contrast.

Cleaning the petals and keyholes

Clean it before and after every use. Master Series says you can boil it in water with a cleaning solution or wipe it with isopropyl alcohol. Open the petals while cleaning so you reach the gaps between them, rinse the keyholes, then dry everything thoroughly. Keep the keys with the plug so they don't go missing, and check the mechanism turns smoothly before each session.

Specifications

• Brand: Master Series, Ass Vault
• Type: locking, expanding anal plug with two keys
• Material: stainless steel, listed as nickel-free
• Overall length: 3.4"; insertable length 2.8"
• Diameter: expands from 1.5" to 2.2"
• Weight: 9.3 oz (264 g), plug only
• Colour: Metal (silver)

See more from Master Series, browse our BDSM gear, or read the guide to safer BDSM.