How to secure my Surface Laptop 7th Edition in public places

Nope - this model does not have a built-in Kensington lock slot, as the chassis is too thin to accommodate one. Here are a few alternatives to consider:

1. Use a Nano Security Slot Adapter You can add a lock slot to your laptop using an adhesive adapter plate. These specialized plates use ultra-strong industrial adhesive to attach permanently to the bottom or back of your laptop, giving you a physical slot to attach a traditional cable lock. For Microsoft Surface devices, the Kensington Nano Security Slot Adapter Kit is certified and allows you to attach any standard NanoSaver lock.
2. The Audio Jack Lock Adapter Even though laptops without lock slots lack traditional locking points, many still have a 3.5mm headphone jack. Several security companies have engineered locks that utilize this port. Products like the Anchor Adapter (available from brands such as Multplx) fit into the audio port and expand with the turn of a screw to secure it in place. This creates a T-bar lock slot that accommodates a standard Kensington cable and blocks removal of the screw once the cable is attached.
3. Universal Laptop Locking Station If you prefer not to stick anything directly to the body of your Surface Laptop, you can use a physical clamping station. Accessories like the Kensington Laptop Locking Station 2.0 cradle the base of your laptop and clamp it in place. You then thread a heavy-duty cable lock through the station, preventing the laptop from being opened or removed.

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hth

Marcin