- Durock Silent Linear Switches are designed with Unique Patent Silent Stem, Removable Silicon Silent circle around the Stem. 2. Durock Dolphin Silent Keyswitch is with Transparent Polymer Nylon lower housing and PANTONE 19-4052 Classic Blue POM Stem. 3. Bottom out force 62g Gold Plated Spring weight and Linear Metal leaf, gold contacts 4. PCB Mount Style - Linear 3.8mm Travel 2mm Operating 67g Bottom Out 5 Pins 50 million operations. 5. Available LED styles - SMD and through-hole.