Key Knob 6 for "B" Size RAM® Pin-Lock™ Security Knobs The RAP-S-KEY3-6U replacement key knob is compatible with the RAP-S-KNOB3-6, RAP-S-KNOB3-6U and RAP-S-KNOB3/RAP-S-KNOB3U mixed combination security knobs that contain the 6 node security pattern. Please verify the node security pattern on your security knob before purchase.