Professional locksmiths and safe technicians use borescopes to read wafer locks (wafer reading scope), look into safe and vault (safe opening scope), and study inside locking mechanism. Here is a good article ( written in 2009) about what to consider when to choose a suitable locksmith scope:  
https://www.locksmithledger.com/keys-tools/article/10229326/factors-to-consider-when-choosing-a-scope

Normally a smaller diameter borescope is good for locksmith technicians for easy access to smaller openings. There are two types of borescopes for professional locksmiths and safecrackers:
  • Rigid 
  • Flexible / Semi-Rigid
For each type, there are two variations: articulating or non-articulation. For articulation type, one can steer probe tip camera to different angles, while for non-articulation probe, usually a side-viewing mirror or another side-viewing camera is needed.  ​

Locksmith Borescopes

Vividia W1149 WiFi Dual-Camera Borescope Videoscope with 4.9mm diameter and 1.1 meter length
$299.98
$299.98

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Vividia FC-3920 Mini 3.9mm Diameter 150mm Long USB Flexible Inspection Camera Borescope Endoscope Microscope with Fixed Focus and Side-View Mirror
$269.98 - $399.98
$269.98 - $399.98

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Vividia FC-520 Mini 5mm Diameter 200mm Long USB Flexible Inspection Camera Borescope Endoscope Microscope with Fixed Focus
$259.98
$259.98
Vividia PM-40 Handheld USB Pen-Type Digital Focusable Microscope Borescope Endoscope Inspection Camera 4.0mm Diameter
$199.98 - $289.00
$199.98 - $289.00

On Sale

On Sale

Vividia AbleScope VA-400 Rigid USB Borescope Endoscope with 180 Degree Articulating 8.5mm (0.33") Diameter Probe and LED Lights
$249.98 - $499.98
$249.98 - $499.98

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VA-400-WiFi Bundle: Vividia Ablescope VA-400 USB Rigid Articulating Borescope plus VA-B2 WiFi AirBox for iPad iPhone and Android Phone and Tablet
$289.98 - $299.98
$289.98 - $299.98

On Sale

On Sale

Vividia GB-430 USB Digital Manual Focus Gun Barrel Borescope with 4mm (0.158") Diameter and 12" (30 cm) Long Insertion Tube
$299.98
$249.98

On Sale

On Sale

Vividia GB-430-WiFi Bundle: Vividia Rigid Gun Borescope GB-430 And VA-B2 WiFi AirBox for iPad iPhone and Android Phone and Tablet
$349.98
$289.98
Vividia PM-54 Handheld USB Digital Microscope Borescope Endoscope with 5.4mm Diameter
$149.98
$149.98

Sold out

Vividia VQ-R39 3.9mm Photo & Video Recordable Flexible Inspection Camera Borescope with 2.4" LCD Monitor
$189.98 - $489.98
$189.98 - $489.98
Vividia VQ-39 Handheld 3.9mm diameter 2.4" LCD Screen Borescope Inspection Camera
$149.98 - $449.98
$149.98 - $449.98
Vividia AbleScope VA-406 USB Rigid Borescope Endoscope with 180 Degree Articulating 6mm Diameter 40cm Long Probe and LED Lights
$399.98
$399.98

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Vividia W2145 WiFi Wireless One-Way Articulation 4.5mm (0.177") Diameter 1,1m (43") Long Borescope Videoscope Inspection Camera for iPhone iPad Android
$969.98
$969.98
Vividia V-3710 USB Flexible Borescope Inspection Camera Videoscope with 3.7mm Diameter 1 Meter Long Probe for PC Mac and Android Devices
$149.98 - $249.98
$149.98 - $249.98
Vividia Q-3920 Borescope Camera Probe Part 3.9mm diameter 2 meter Long for VQ-39 and VQ-R39 Models
$99.98
$99.98

On Sale

On Sale

Vividia W2240 WiFi/USB Wireless USB 2-Way Articulation 4.0mm 0.157" Diameter Borescope Videoscope Inspection Camera for Windows iPhone iPad Android MacBook Chromebook PC
$999.98 - $1,199.98
$949.98 - $1,099.98