2.5v Medical CompacSetâ„¢ with Charging Transformer and Rechargeable Battery. CompacSetâ„¢, the ingenious portable diagnostic set from Welch Allyn, is the only diagnostic set that integrates a full-featured ophthalmoscope and fiber optic otoscope into one durable, easy-to-use instrument. Portable and protected, the CompacSetâ„¢ is small enough to fit in any pocket, weighs just 8.5 ounces, and, when not in use, is fully protected by a durable ABS plastic housing. It is the first set designed specifically to make life easier for busy practitioners. It makes a perfect "second set" -- one that can be kept with you at all times, no matter where you are.