Outdoor Microducts
The ‘basic’ fibreflow microduct assembly has an aluminium water barrier, bonded to the sheath. It is soft temper so that under moderate stretching, it will not fracture.
The sheath is polyethylene (PE), with good flexibility and toughness, such that it is ideal for use installed inside a pre-installed duct or subduct. Yet it can be removed using the pre-installed ripcord.
Thus we have a low weight, low cost product, with great flexibility.
It is in effect, an EMPTY fibre optic cable.
One advantage is that this product can be installed easily using standard cable practice, with very low installation force (these lengths can often be pulled in place by hand, ideal for low-tech countries) and there is no tensile risk to fibres, since they are installed later, when required.
2. DIRECT BURY (DB) INTO THE GROUND
The fibreflow DB version is basically the DI product with an additional heavy-duty sheath added. 
It can be dropped into dug trenches without special handling. The outer sheath is tough PE, normally 2mm thick, making the product very rugged. It is almost a subduct in its own right, and yet takes up less space. 
DB laid in a trench
DB is also available in metal-free versions:
7DBmf
3. DIRECT BURY with REINFORCEMENT (DBR)
The fibreflow DBR version of the direct bury has an intermediate layer of high tensile e-glass, which imparts tremendous extra longitudinal strength.
This product can withstand being accidentally dug up by a trenching machine. eg The 19 way DBR is tested to extend only 1% at 1 ton load. The e-glass layer also imparts resistance to rodent damage.
Another design to resist rodent attack incorporates steel armour tape. Corrugated and folded, this thin steel barrier provides even greater protection than e-glass, though it requires a different method of stripping. Steel armour is available under DB sheaths or LF sheaths.
This steel-armoured bundle has a LFH 7-way inside the steel, and also benefits from greater resistance to ignition than normal. Ideal for indoor use where rats may be present, such as large building complexes, campus, stations etc.
Tube bundles can also be deployed overhead, as self-supporting runs. or lashed to existing aerial messenger wire.
