Because it stacks - one end fixes, the other receives, so layers chain upward.

Each level of an assembly can be added or removed independently, which is what multi-board and multi-panel work needs.

Servicing a middle layer means removing only what is above it, rather than dismantling the whole stack.

It also reduces the number of separate parts, since the standoff replaces both a spacer and a fastener at that joint.

Female-female standoffs need a screw at both ends, and male-male need a nut or a tapped hole at both.

Where only a single gap is being set between two parts, any of the three will do the job.

Body length and male thread length are quoted separately, and both matter for different reasons.

Body length sets the actual gap between the two parts, which is usually the dimension the design specifies.

Male thread length has to pass through whatever it goes through and still engage properly in the tapped hole or nut beyond.

Ordering on body length alone is the common error, and it produces a standoff that sets the right gap and cannot be secured.

Overall length is sometimes quoted as well and is the sum of the two, so it is worth confirming which figure a catalogue means.

Where the male end goes into a blind hole, the thread length must also not bottom out.

At least the manufacturer's stated minimum, and not so much that the screw bottoms out in a blind tapping.

Too little engagement concentrates load on the first threads and strips them, usually without warning.

A bottomed screw is the less obvious failure - it stops turning and feels tight while providing no clamping force at all.

Standoffs are made with both through and blind tappings, and which one is supplied changes the usable screw length.

A through tapping is more forgiving, since excess screw length simply protrudes.

Checking the tapped depth with a rod before choosing screw lengths takes moments and prevents the whole problem.

Hex where the standoff has to be tightened or held; round where clearance or appearance decides.

Tightening the male end into a tapped hole needs the body to be gripped, and flats make that straightforward.

Round bodies take less space on the diagonal and look cleaner in visible assemblies.

Knurled round bodies are a compromise, giving finger grip without flats.

In polymer standoffs the flats round off easily under a spanner, so hex helps less than it does in metal.

For assemblies built by hand rather than by machine, hex is generally the more practical default.

Metal where the thread carries load, polymer where isolation and weight dominate - and the thread strength difference is large.

Brass and steel standoffs carry substantially more thread load than nylon ones of the same size.

Nylon and other polymers give electrical isolation, which is often the reason they are chosen in electronics.

Polymer threads also strip at much lower torque, so assembly torque has to be controlled.

Aluminium is light and machines well; stainless suits demanding environments at higher cost.

In mixed-metal assemblies a polymer standoff breaks a galvanic path that a metal one would create.

For light panel and board work yes; for anything carrying real load they are not designed for it.

Standoffs are made to set a gap and secure a light assembly, not to carry structural load.

Their weakest point is usually the thread engagement rather than the body.

Side loads put the body into bending, which slender standoffs resist poorly.

Where a panel carries weight or is subject to impact, a bracket or a structural pillar is the right part.

Increasing the number of standoffs distributes load better than increasing the size of a few.

By adequate thread engagement, controlled torque, and where necessary a thread-locking compound or a locking fastener.

A standoff tightened properly into a tapped hole behaves like any other threaded joint, and adequate preload is the first defence.

Vibration is the usual cause of loosening in equipment assemblies, and a thread-locking adhesive is the common answer in metal.

Polymer threads tolerate very little torque, so mechanical locking is preferable to tightening harder.

Locking fasteners at the screwed end address the screw rather than the standoff's own male thread.

In stacked assemblies, a standoff that loosens at its base is often only discovered when the whole stack moves.