A knob is used in knob and tube wiring to allow the wires to be strung along a wall or ceiling.
There are two basic kinds of knobs, clamp knobs and wrap knobs. The first three pictures show clamp knobs, where the knob is made in two pieces with one or two channels in the top and bottom for one or two wires to fit in. The knob has a central nail that anchors the knob to the the wall or ceiling sandwiching the wires between the two pieces of the knob. Clamp knobs come in glazed and unglazed (shiny or not shiny).
The fourth picture shows wrap knobs, where the wire is not sandwiched between two pieces of the knob but tied around the channel in the one-piece knob. These were often used in conjunction with clamp knobs where the wire had to turn a corner but were also used for running the wires in straight lines. We have encountered maybe one unglazed wrap knob ever in over 20 years of dealing in them. The wrap knobs come in different sizes, as you can see in the picture. For more information, please see our full description of knob and tube wiring. Wikipedia's knob and tube wiring page has great pictures of knob and tube installations.
We don't always have all types, glazes, and conditions of knobs. When we are out of stock of a particular condition, the option will be grayed and crossed out. It's best to give us a call to see if we are really out of the type you want. The computer counts are not always accurate or we may be expecting a shipment.
This product is one set of the ceramic pieces, the shorter top piece, the bottom piece, and the nail in the case of a clamp knob, just the one knob in the case of a wrap knob. The wire is not included. Please see the Knob & Tube Supplies collection for more knob and tube items.
New Old Stock
If we find knobs that have never been used we call them new old stock. They're in new, never-used condition but they were made decades ago. We almost never find these, but very occasionally will come across some.
Knobs classified as good may have slight chips, a little dirt, slightly bent nails.
Knobs in fair condition are still functional, but may have larger chips but no major breakage, and can have significant dirt, marks, and/or discoloration.
We Buy These!
See our We Are Buying page to see the steps to take to sell us knobs, tubes, and cleats.