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ABUS thumbturn lock cylinder

Updated: October 2026

You want to lock from inside without leaving a key in the door, and you still need a key outside. An ABUS thumbturn lock cylinder is the right inside when nobody outside can reach the turn. It is the wrong inside when a letterbox, a cat flap or glass lets someone operate the knob. Peter F. updated this in October 2026. The three knobs are the only thumbturns in the [ABUS lock cylinder comparison](/hub/door-and-window-security/abus-lock-cylinder). We did not run a lab test. A qualifying purchase can earn a commission at no extra cost to you. Split first is the [ABUS lock cylinder buying guide](/hub/door-and-window-security/abus-lock-cylinder/sub/abus-lock-cylinder-buying-guide).

You want to lock from inside without leaving a key in the door, and you still need a key outside. An ABUS thumbturn lock cylinder is the right inside when nobody outside can reach the turn.

Our top picks

ABUS ABUS KD6PS Z50/K30 thumbturn

Best overall

ABUS ABUS KD6PS Z50/K30 thumbturn
9.4/10about £30.19
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ABUS ABUS KD6XNP Z30/K30 thumbturn

Rank 2

ABUS ABUS KD6XNP Z30/K30 thumbturn
9.2/10about £36.74
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ABUS ABUS KD6PSN Z35/K35 thumbturn

Rank 3

ABUS ABUS KD6PSN Z35/K35 thumbturn
9.2/10about £33.01
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On this page
  1. 1.When the turn is the right inside
  2. 2.When glass or a letterbox rules it out
  3. 3.The three ABUS thumbturns in this set
  4. 4.What to check on the door before you order

When the turn is the right inside

A thumbturn replaces the inside key. You turn the knob to throw the lock, and you use a key from the outside. Reviews of the KD6XNP describe flat doors and house doors where people can still get out, and an outside key that still opened the door after it was locked inside. On the Z50/K30, reviews say children found the inside turn practical. That is the use, not a security grade. Measure both sides before you pick one of the three. A thumbturn cannot be reversed, because the knob finishes indoors. If you are happy to remove an inside key, stay with a double. The reach test comes before any ASIN.

When glass or a letterbox rules it out

West Yorkshire Police tell you not to leave keys in reach of the letterbox, a cat flap, or on view through a window. A thumbturn has the same reach problem. If a hand or a tool can get to the knob, the door opens. Lock Guy’s UK article says to avoid a thumbturn when the letterbox can fish the turn, or when nearby glass can be broken. A dormakaba TS 007 note says the knob should not be operable from outside through glass. If the door fails that test, keep a key both sides. In a flat or an HMO, the responsible person or a locksmith decides. London Fire Brigade guidance on a single inside fastening is not a rule that every house needs a thumbturn.
ABUS ABUS KD6PS Z50/K30 thumbturn

Testsieger

ABUS ABUS KD6PS Z50/K30 thumbturn
9.4/10about £30.19
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The three ABUS thumbturns in this set

On these titles, K is the knob and Z is the key. The knob goes inside. The KD6XNP Z30/K30 is about £36.74 and shows 4.5 from 371 reviews. It is an equal 30/30. The listing states an emergency function, so an outside key still works after you lock it from the knob. There is no anti-snap line. Reviews say the knob sits off centre. The KD6PSN Z35/K35 is about £33.01 and shows 4.5 from 209 reviews, an equal 35/35. The bullets state a programmed break and do not use the emergency-function sentence. The KD6PS Z50/K30 is the top pick at about £30.19, on 4.6 from 1,039 reviews of this ASIN: 50 mm on the key side and 30 mm on the knob. Pre-snap is stated. The bullets do not state an emergency function. One review says an outside key still opened it. That remains a review. Which split fits is the best ABUS lock cylinder page.

What to check on the door before you order

Z30/K30 only suits 30 mm both sides. Z35/K35 only suits 35 mm both sides. Z50/K30 only suits 50 mm on the key side and 30 mm on the knob. Put the K side indoors. The screw-out sequence is the how to fit a euro lock cylinder page. The KD6XNP knob sits off centre, so reviewers bought a separate rose. An Escurra case on the Z50/K30 needed a larger rose. A thumbturn does not replace a TS 007 cylinder. The two D6PS knobs print a programmed break, which is not a three-star Kitemark, and the Z30/K30 prints no snap line. If the turn can be fished, stay with a double cylinder.

Common questions

What is the point of a thumbturn if I still need a key outside?
The outside stays a key. The inside becomes a knob, so you lock up without leaving a key in the door. Reviews mention that for flat doors and for children. You still need the outside key, and the knob still has to be out of reach from outside. The turn is everyday use, not a security grade on its own.
Which side of Z50/K30 is the knob?
On this listing, K30 is the knob and Z50 is the key. The knob goes inside. The split is unequal, 80 mm overall, so the 50 mm side is not automatically outside until you measure. The same K-for-knob reading applies to the Z30/K30 and the Z35/K35. Do not swap the letters to match a different ABUS family.
Which of the three states that an outside key still works after you lock inside?
Only the KD6XNP Z30/K30 states that emergency function, at about £36.74. The Z35/K35 and the Z50/K30 do not print it. One Z50/K30 review says an outside key still opened the door. Treat that as a review, not as the bullet. If something may be left in the cylinder, the stated listing is the Z30/K30, and only at a 30/30 split.
Is a thumbturn safe on a door with a letterbox?
Not if the letterbox is close enough to reach the turn. West Yorkshire Police warn against keys within reach of a letterbox or a cat flap, and the same route works on a knob. If you cannot guard the opening, keep a key both sides and take the inside key out. A thumbturn does not remove that reach problem.
What about a glass panel next to the handle?
If breaking the glass lets someone operate the knob, do not fit a thumbturn there. The dormakaba TS 007 note says the knob should not be operable from outside through adjacent glazing. If it is, use a double cylinder or make the glass resistant. Laminated glass is a suggestion from UK guides. It is not supplied with these listings.
Will a round rose cover the KD6XNP knob?
Often no. Reviewers bought a separate rose because the knob is not central, and the listing does not include one. The knob is also described as hard to turn, and the keys can be stiff when new. If your furniture needs a centred round rose, budget another rose or choose a different inside.

Related pages

Anti-snap euro cylinder and TS 007

ABUS lock cylinder

Best ABUS lock cylinder: which listing fits the door

ABUS lock cylinder buying guide: split, then family

How to fit a euro lock cylinder and stay within 3 mm

Sources

Public sources from the research digest, last checked on 21 October 2026. Prices and review counts are amazon.co.uk listings, not a laboratory test.

  1. ABUS D6XNP double cylinder (retrieved 21 October 2026)
  2. ABUS D6PS door cylinder (retrieved 21 October 2026)
  3. ABUS XP20S cylinder (retrieved 21 October 2026)
  4. ABUS UK door cylinders (retrieved 21 October 2026)
  5. ABUS UK X60 cylinder (retrieved 21 October 2026)
  6. Sold Secure listing for the ABUS X60 euro cylinder (retrieved 21 October 2026)
  7. BSI certificate KM 778080 (E60 and Vela, one-star) (retrieved 21 October 2026)
  8. ABUS on code cards and security cards (retrieved 21 October 2026)
  9. West Yorkshire Police euro-cylinder advice (retrieved 21 October 2026)