Only Heat and bond light is currenlty available on a bolt. The other ( heavy or the kind you should not try to sew through) is now only available in pre cut lenghts in a package. It is possible you purchased from a bolt that has been hanging around for awhile , but its been over a year thatheat and bond stopped selling the regular or heavy on bolt.
Look at the edge of the heat and bond ( paper side) there is a printing about every 1/2 yard on the edge in pink ( it says Heat and Bond). If it is in pink you have the light.