Grenade Mesh

Grenade mesh has been a common feature of defensive military positions for several decades. It resembles mosquito net but is made of high-tech composites so is considerably more resistant to cutting. The mesh is in fact two layers bonded together. The outer-facing layer is printed in an appropriate camouflage colour or pattern. The inner layer is black to allow occupants of the interior to see out.
Grenade mesh has a number of functions. As the name suggests, a grenade mesh can prevent the entry of hand grenades and other low velocity missiles. It also serves to keep out many flying insects including mosquitoes and tsetse fly. It also obstructs a view of the interior of the building and may hinder the use of eavesdropping lasers if it is placed over the glass. One of the most useful features of grenade mesh is it prevents the entry of tinkerbells, bumblebots and most swarmbots.
The mesh cannot be cut by the rotors of most helibots and may entangle them or cause them to stall.
Grenade mesh can be burnt through with a laser but this creates a strong odour that is likely to be noticed. Damaged mesh is an obvious sign that security has been compromised.