Door Gap Measuring Tool, 1-15mm Fire Door Gap Gauge Checker Tool Engineering Ruler, Feeler Gauges for House Engineering Inspection Flatness Measuring Tool Ruler(0.5mm/0.2mm) (0.5mm)

Useful tool - good for periodic checks on fire doors to ensure no movement needs addressing. I wasn’t sure whether you take the reading from the narrow side or wider side of the slider as it doesn’t tell you on the device or packaging - an experienced fire door inspector, who uses a similar tool, told me it’s the measurement on the narrower side that’s relevant, i.e, the side of the slider that touches the door/ frame.Very easy to use and good value for money. I bought this one another wider one, shaped more like a credit card - using both helps confirm accuracy of the readings I found. Happy overall although I feel clear user instructions would be useful.

Better than the usual plastic door gap and much more accurate.

Fair item, I was expecting a bit more functionality then this but its dine not bad.The compatibility is fairly good as well

Does the job

Exactly as it says works fine

That tool dont work for the doors as doors are shaped all the time and not square,my tool says 4mm this tools says 6.5mm,maybe it works for old door but not for new in uk.

Used these on a job with very strict regulations on fire doors, very accurate and fits easily in your pocket or tool belt, a must with high end finish jobs. 👌🏻 Found the best way to use it is have the slider set away from the door margin until its inserted then slide it to the door for a more accurate read.

It's 'close enough' for joinery work, but for gaps of just a few millimetres it's not as accurate as I had hoped.I can probably improve it by grinding the back surface carefully.