CarlRM-15/2 15-Inch Cutting Mat for all 15-Inch Trimmers,Gray

Our xacto 26432 rotary trimmer is 25+ years old; it used replacement parts made by boston. it uses a 15" mat. could this work if cut?

How wide is the cutting mat? I need it for a Fiskars trimmer.

I bought a 7/16" wide replacement mat and it won't fit my older Fiskars cutter. Can anyone tell me if this is 3/8" wide?

are these really for the 15" Trimmer? Based on the comments it is 18 inches