The ad for this in Popular Science says:
The "Handyman" is an all-in-one unit to save valuable service time - Cheater Cord with on/off switch, Dual Extension Cord, updated Filament Checker, Universal Fuse Checker, Handy Trouble Light, Neon Voltage and Continuity Checker, Pin Straightener and Cord Wrapper - all in a single compact unit.
see link for additional detail :https://www.etsy.com/ie/listing/631245284/vintage-sencore-handyman-model-hm-119?show_sold_out_detail=1&ref=nla_listing_details