Print Back
These standoffs ensure permanent mounting in metal sheets as thin as 1.60mm.

The fastener head is locked securely in a blind, milled hole and is able to handle substantial loads. The concealed-head feature allows the side of the sheet opposite installation to remain smooth.

Sheet preparation only requires a milled blind hole to the recommended minimum depth. Center-cutting end mills for hole preparation are available from PennEngineering. Installation of the concealed-head studs and standoffs is simple using a hollow anvil and solid punch. Place the head of the fastener in the hole and insert using any standard press. Displaced sheet metal flows smoothly around the head into the undercut.
Concealed-head standoffs - CSOS, CSS
Stainless Steel Standoffs - Types CSS, CSOS 2
Unit of Measure
Items Concealed-head standoffs - CSOS, CSS
CSS-M3-4
Stainless Steel Standoffs - Types CSS, CSOS - Metric
Concealed-head standoffs - CSOS, CSS
CSS-M4-4
Stainless Steel Standoffs - Types CSS, CSOS - Metric
Concealed-head standoffs - CSOS, CSS
CSS-M5-4
Stainless Steel Standoffs - Types CSS, CSOS - Metric
Concealed-head standoffs - CSOS, CSS
CSS-M3-6
Stainless Steel Standoffs - Types CSS, CSOS - Metric
Concealed-head standoffs - CSOS, CSS
CSS-M4-6
Stainless Steel Standoffs - Types CSS, CSOS - Metric
Thread Size x Pitch N/A M3 x 0.5 N/A M4 x 0.7 N/A M5 x 0.8 N/A M3 x 0.5 N/A M4 x 0.7
Thread Code N/A M3 N/A M4 N/A M5 N/A M3 N/A M4
Length Code N/A 4 N/A 4 N/A 4 N/A 6 N/A 6
Material Code N/A S
Style N/A #1
Shank N/A Short
Min. Sheet Thickness N/A 1.6 mm
Blind Mounting Hole Diameter + 0.08 N/A 5.41 mm N/A 7.92 mm N/A 8.74 mm N/A 5.41 mm N/A 7.92 mm
Min. Depth of Blind Hole1 N/A 1.10 mm
L - Length + 0.05 –0.13 N/A 4 mm a1391.jpg N/A 4 mm a1391.jpg N/A 4 mm a1391.jpg N/A 6 mm a1391.jpg N/A 6 mm a1391.jpg
A Max. N/A 1.04 mm
B Max.2 N/A 4.20 mm N/A 6.23 mm N/A 7.37 mm N/A 4.20 mm N/A 6.23 mm
C Max. N/A 5.39 mm N/A 7.9 mm N/A 8.72 mm N/A 5.39 mm N/A 7.9 mm
H Nom. N/A 6.35 mm a1394.jpg N/A 8.74 mm a1394.jpg N/A 9.53 mm a1394.jpg N/A 6.35 mm a1394.jpg N/A 8.74 mm a1394.jpg
Min. Dist. Hole C/L to Edge N/A 4.8 mm N/A 6.4 mm N/A 7.2 mm N/A 4.8 mm N/A 6.4 mm
For Use in Sheet Hardness N/A HRB 70 / HB 125 or Less
Thread Specification N/A Internal, ANSI / ASME B1.13M, 6H
Fastener Material N/A 300 Series Stainless Steel
Standard Finish N/A Passivated and/or tested per ASTM A380
Min. Depth Full Thread F N/A 5 mm N/A 6.5 mm N/A 9.6 mm N/A 5 mm N/A 6.5 mm
CAD Supplier N/A PennEngineering® (PEM®)
  • 1 Blind mounting holes may be deeper than minimums except where sheet material is at or near minimum thickness. Fasteners should always be installed so the flange is flush with the surface of the sheet.
  • 2 If standoff is used as a bushing, the hole in attached part must not exceed “B” plus .020” / 0.51 mm.