I have tried to keep the size perspective in the two pictures of the SX-101A (top) and the SX-115 (bottom).

There were 3 different models of the SX-101 manufactured:
1. The SX-101 introduced in 1956 (collectors $350 08/00) Included 7 ham bands 160-10 plus 10MHz. WWV spot. 14 tubes and sold for $395 without the R47 matching speaker.
2. SX-101 Mark III (collectors $350 08/00) introduced in 1958. Included 7 ham bands and had 13 tubes. It sold for $395 without matching speaker.
3. SX-101A (collectors $450 08/00) is similar to the SX-101 Mark III with the exception this receiver covers ham bands 80-10 and incorporates the scales for 2 meters and 6 meters. The unit will pair nicely with the HA-2 and HA-6 transverters. This unit sold for $399.50 less the R47 speaker which would cost an additional $12.95 (collectors $70 08/00).

The SX-115 was introduced in 1961 (collectors $800 08/00) This unit is triple conversion (SX-101 dual conversion) and covers 80-10 meters plus 10MHz. WWV. The VFO included temperature compensation. The matching transmitter is the HT-32B.