It is often useful to measure the pressure in a dropped soffit over the kitchen cabinets, for example, that may be accessed through a small opening beside a mounting bracket or light fixture housing. (Check out the picture. The pressure in this house was -50 WRT outside. The pressure in the dropped soffit was -29 WRT outside. Definitely worth getting into the attic and finding the gap.) There may be gaps in stair risers over an unconditioned basement that will accept the probe tip. Or it may be possible to create a small opening in a porch ceiling or wall cavity that can easily be refilled. There is no magic to the length of the tube. It can be shortened if it gets damaged, and it can be bent to adapt to specific situations.
