SK‑116* Physical Characteristics
| Number of Pins: | 11 |
| Pin Circle Diameter: | 9.4mm (0.370") |
| Pin Diameter: | 0.45mm (0.018") |
| Pin Spacing: | 10 × 30° |
| Alignment Method: | Pin Gap, 1 × 60° |
NOTES:
* I do not yet know any correct designation for this tube base type; "SK‑116" is the part number of a compatible socket.
Some tubes with this base have the evacuation/fill nipple in the center of the base, requiring compatible sockets to have a matching center hole specified as 5.2mm (0.205") diameter with minimum 7.0mm (0.276") depth.
Some (most?) tubes with this base type are actually made with 12 pins and the gap created by cutting one pin. Since I know of no instance in which this 12th pin is not cut, and all sockets appear to be 11-pin, I consider this to be an 11-pin base.
Pins are shown as looking at the base of the tube; i.e. "bottom view".