One Adapter fits All: The universal pen adapters are made for all pens, markers, tools with a diameter less than 0.5 in; over 100 pens have been tested repeatedly during the research and development section to fulfill the performance of a smooth drawing and sketching. Fits Most Cricuts: The CRAVERLAND universal pen adapters are compatible with the Cricut Explore 4 3, Maker 4 3,Air 3,Air 2, Air, Maker,Explore,Venture; Not for Cricut Explore ONE and Joy;the pen adapter will slide down into the pen clamp smoothly. Fits All Brands Pens, No More limits: The CRAVERLAND universal pen adapter is compatible with (Sharpie,Crayola,Paper mate,Bic,Stabilo,Pilot,Sakura,Tombow,Pentel,Cricut)and other pens/markers, fits over 20 brands names. Brand's names and trademarks are shown for compatibility only. Easy Operation:The pen adapter was initially designed by CRAVERLAND with a compact design and easy to operate with; it comes with an instruction easy to read in the package. Central and Depth Calibration Required: Better have a test before running a project, for there will be a minor deviation of the centre because of the design. Also, a depth calibration is inevitable to fit varieties of pens. Gift Box Design Also an Organizer: the pen holder set includes 2 adapters and 4 calibration units organized in an original-designed Juno's bird gift box, so the whole bundle is convenient for own collection, organization, or as a gift to friends love crafting. Easy to clean:the calibration units and adapters can be cleaned by a wet wipe and used repeatedly,so you will not need more pieces of them,this set is enough