The Kay Thin Twin, was first produced in 1952, in Chicago, Illinois, and remained in production until 1959. It was a real Chicago Blues guitar, and although most associated with Jimmy Reed, was also widely used by his contemporaries, and blues musicians ever since.
The guitar was a hollowbody, 2 3/4" thick - not a thinline as the name might imply - all maple with a set neck. 'Thin Twin' refers to the pair of very narrow single coil pickups fitted to the guitar, and it's these along with the maple construction that give it it's characteristic biting tone.
The following description comes from the 1959 Kay catalogue
Kay Thin Twin "II" - For real drive. A Kay exclusive! Adjustable reinforced slim neck. Thin, aud. size. Twin adjustable units, 3-way switch, separate controls' Laminated Curly Maple body, Natural blonde top, shaded back and sides with sunburst; hand-rubbed. $150
This was not a cheap guitar at $150 - at the same time (1959) the non-cutaway Gibson ES-125 was broadly similar in price at $159.50.
$1895
$2500
$1895
$2195
$1449
$550