These Pyle ‘transformers’ should NOT be used where galvanic isolation is required, or where ground leakage can become shock hazard. Images do not indicate any safety approvals by a NRTL, so would be disallowed for use in the work-place per 29CFR1910.
As the typical ferro-resonant regulator is > $350 for a 1kW unit, and a true isolation transformer is well over $1000 for a 5kW unit, would have to believe that the construction of these units are an inherent shock hazard.
I took a close look at the photo for the “Pyle PSPL03 Sound Lever Meter” and had a good laugh. Unfortunately that doesn’t portend well for the unit’s accuracy.
A lot of misinformation here. First, step-up and step down transformers are not inherently dangerous. Transformers have been around since the 1800s, and we use them every day in tons of gadgets and gizmos.
And for the NRTL, that’s a bit extreme. Go look around at workplace electronics: hand driers in the bathroom, your computer monitor, etc.