Global Specialties Experimentor 350 Series breadboards.  270 contacts, organized in 12 rows: 2 power rails (20 pins each), and 23 columns of 5 and 5 contacts for DIP ICs and all other components.  Nice 3-1/2" x 2" size for small projects, and can be interlocked together (horizontal and vertical) for bigger circuits.  Same as Radio Shack / Archer 276-175.  Also known as EXP-350.

Breadboards are used, but in good overall condition.  Some have a bit of yellowing, but are clean and with minimal wear.  A few positions were used more than others, but all contacts make good connection with wire and component leads.

Listing is for 3 pieces.  Contact me if you need a larger quantity (for discounted lot price and combined shipping).

Thanks for looking.