A: Yes it will, however I would not recommend using the pins on fiberglass as you don't want to create holes in the fiberglass.
A: If slabs is referring to concrete, then no. This unit is not able to detect moisture in concrete as the material interferes with the sensor due to its conductivity.
A: Hi Jimmy. Thank you for your question. This is an online item that is not carried in our stores. https://www.homedepot.com/p/General-Tools-9-in-1-Thermo-Hygrometer-Pin-Pinless-Moisture-Meter-with-Probe-and-Carry-Case-RHMG650/205078069#product-overview https://images.homedepot-static.com/catalog/pdfImages/b9/b99317d4-9340-498a-8092-7bd22053aa92.pdf Please let us know if we can be of further assistance. Rick_HD_OC
A: No it wont detect moisture through metal