
Concealed Head Standoffs
Threaded standoffs fitted into a blind hole, hidden from the front.

Closed-end threaded spacers, sealed on one side.
Blind standoffs are closed at one end, so the screw cannot pass through and the panel stays sealed. They press into thin sheet and hold boards or parts at a fixed height.
Full dimensions, preferred lengths and installation / push-out / torque-out performance data are in the tables below, taken from the self-clinching fasteners catalogue.
| Part numbers | SG-BSO, SG-BSOS, SG-BSO4, SG-BSOA |
|---|---|
| Zinc Plated Steel | SG-BSO |
| Stainless Steel | SG-BSOS |
| 400 Series Stainless Steel | SG-BSO4 |
| Aluminium | SG-BSOA |
| Sizes | M2, M2.5, M3, M3.5, M4, M5 |
| Sheet hardness (SG-BSOA) | HRB 50 or less |
All dimensions in mm unless stated. Values from the self-clinching fasteners catalogue. Install into sheet within the hardness limits shown in the specifications.
| Thread | M2, M2.5, M3 | M3 alt | M4 | M5 |
|---|---|---|---|---|
| C -0.13 | 4.2 | 5.39 | 7.12 | 7.12 |
| A nom. | 4.8 | 6.4 | 7.9 | 7.9 |
| Min. sheet thickness | 1.0 | 1.0 | 1.27 | 1.27 |
| Recommended hole size +0.08 | 4.22 | 5.41 | 7.14 | 7.14 |
| Min. distance to edge of sheet | 6.0 | 6.8 | 8.0 | 8.0 |
| Length L | 5 | 6 | 7 | 8 | 10 | 12 | 14 | 15 | 16 | 18 | 20 | 22 | 25 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thread depth B min. | 2.8 | 3.2 | 3.6 | 4.0 | 5.0 | 6.5 | 9.5 | ||||||
| Thread | M2, M2.5, M3 | M3 alt | M3.5, M4 | M5 |
|---|---|---|---|---|
| Installation (kN), steel and stainless | 9.9 | 14.8 | 17.9 | 17.9 |
| Torsional resistance (Nm), steel and stainless | 2.16 | 3.95 | 8.5 | 8.5 |
| Pushout (N), steel and stainless | 1050 | 1870 | 2500 | 2500 |
| Pull-through (N) – steel | 1470 | 1470 | 3180 | 3180 |
| Pull-through (N) – stainless | 1180 | 1180 | 2490 | 2490 |
| Max. torque for mating screw (Nm) – steel | 0.56 | 0.56 | 2.1 | 3.7 |
| Max. torque for mating screw (Nm) – stainless | 0.45 | 0.45 | 1.7 | 2.9 |

Threaded standoffs fitted into a blind hole, hidden from the front.

Threaded spacers open at both ends.

Unthreaded spacers for a screw that passes right through.

Snap-top standoffs: push the board on, no screw needed.

Standoffs with a locking thread that resists screw loosening.

Keyhole-mount standoffs that slide and lock a board in place.