TND 750

Yes. 

1. Go to Settings (gear icon) on the launch screen
2. Scroll down on the General tab and tap System settings
3. Tap Security & location

Here you can enable a password, pattern lock, PIN, etc.  Use this to protect your information stored on the device.

TND 550

Yes. 

1. Go to Settings (gear icon) on the launch screen
2. Scroll down on the General tab and tap System settings
3. Tap Security

Here you can enable a password, pattern lock, PIN, etc.  Use this to protect your information stored on the device.

TND Tablet 85

Yes.  Tap the Android Settings icon and scroll down to Security & location.  Tap on Screen lock and here you can enable a password, pattern lock, PIN, etc.  Use this to protect your information stored on the device.

TND Tablet 70/80, RV Tablet 70/80

Yes. Swipe down from the right side of the screen to view settings. Tap the settings button. Scroll down to "Security." There you can enable a password or pattern lock that must be entered each time the device is powered on. Use this to protect your information stored on the device.