One of the categories of Mukse is Keli She'm'lachto L'isur-a utensil whose primary function is prohibited on Shabbat. The Hachamim permitted moving such an item only L'sorech Gufo-for another permitted function or L'sorech M'komo-for its place.
One example of Keli She'm'lachto L'isur is a sewing needle, as its primary purpose is for sewing which is prohibited. It would be permitted to use it to remove a splinter, L'Sorech Gufo. The same applies to knitting needles.
The Poskim define rulers and scales, as Kelim She'm'lachtam L'isur, since it is prohibited to measure on Shabbat. This applies to non-digital scales as well. It is only permitted to use a food scale for the purpose of a Misva, such as measuring Masa or Maror for the Misva on Pesah.
Other examples include: calculators, radios and flashlights. Accordingly, if someone wanted to move his clock radio to see the time, it would be permitted, as that would constitute L'sorech Gufo, as long as he is careful not to pull out the plug. He would also be permitted to move the clock radio from the dresser, L'sorech M'komo, in order to make space for something else that he wants to put there.
A car is Keli She'm'lachto L'isur. If someone forgot food in the car before Shabbat, he may open the door or trunk to remove the food. This is considered L'sorech M'komo, since the closed door is blocking access to the food, it may be moved out of the way. Of course, this leniency applies only to rare cases in which opening the car door or trunk does not activate any lights or electric circuits. Also, there is no rationale to permit directly closing the door after removing the needed items.
Clothes that were left in a closed electric dryer before Shabbat may be removed on Shabbat, assuming that opening the dryer door does not activate lights or electric circuits. Like the car, the leniency is because the door is a Keli She'm'lachto L'isur and opening the door is L'sorech M'komo. It would not be permitted to directly close the door after removing the clothes.
Electric fans and electric blankets are Kelim She'm'lachtam L'isur, and may be used as long as they were plugged in before Shabbat. Of course, the dial or button may not be adjusted. It is permitted to move the fan to bring the flow of air closer, since that is considered L'sorech Gufo. Likewise, the fan may be moved so that the flow of air blows away from him, since that is considered L'sorech M'komo.
Percolators, crockpots and coffee makers are classified as Keli She'm'lachto L'isur. If they have water inside of them, it is permissible to move them as needed. If not, they may be moved only L'sorech Gufo and L'sorech M'komo, e.g. remove them from the counter if their space is needed.
Other examples of Keli She'm'lachto L'isur include:
extensions cords
adapters
scissors
Shabbat timers
nail clippers
fly swatters
regular pens (as opposed to special artist pens or quills which would have a stricter classification.
hole punchers, staplers
umbrellas
hair brush and comb
gardening tools such as hoes, rakes and sprinklers
Wallets- There is a Machloket (disagreement) between Ashkenazim and Sepharadim regarding wallets. When it has money in it, it is clearly Mukse as a Ba'sees (base) and may not be moved at all. However, if there was no money in the wallet, Ashkenazim are strict since it is designated for money. However, Maran in 310:7 rules that it is permissible. Similarly, an empty Sedaka pouch or an empty case of a musical instrument is also not Mukse.
Toothbrush- According to the Poskim that brushing teeth with toothpaste is prohibited, a toothbrush is a Keli She'm'lachto L'isur. Hacham Ovadia has a famous ruling to permit the use of toothpaste on Shabbat, in which case the toothbrush is not considered Mukse at all.
