[sdiy] what are these?

[Roy J. Tellason]

I'm still sorting through parts...

In this small bag labeled "optoisolators" I find these five things.  About an 
inch long more or less,  mayba a cm wide,  and irregular in contour -- there 
are two wires coming out of each end,  and the rest is covered by a layer of 
heatshrink.  Markings are "SIGMA 932" and "301T1-PC" and "26148".  I'm not 
measuring anything with an ohmmeter between pairs of wires...

Reminds me a little bit of those units that Fender used to use for "vibrato" 
except that these were obviously mounted on some board or other,  wires are 
fairly short and all pointed in the same direction.

Any of you guys have any ideas about these?