This is the 2nd generation silent pushbutton by Sanwa Denshi.  The first generation, which will still be offered, uses a foam pad that sits inside the body to absorb the plunger each time it's pressed down

To some players, the mushy feel was not pleasant, while others are fine with it.  Sanwa Denshi received feedback from many players to create a silent button didn't require the foam, which they have done here

The current microswitch that is in all Sanwa Denshi pushbuttons in their OBSF line is silent natively.  The noise though from each button pressed was caused actually by the side clips of the plunger rubbing against the body of the button.  With this, Sanwa took the clip tabs off (redesigned the mold) with a single point of contact holding the plunger to the microswitch itself.  Sanwa Denshi took it one step further and change the composite of the plastic used for both the plunger and body to reduce the vibration (noise)

The result?  A much improved silent pushbutton that feels like the original OBSF30, without the mushy feel

Quick Link: 

Currently, the first batch will only be available in the following colors:

• Black
• K / Dark Blue
• K / Dark Hai
• Red
• Royal Blue
• White