Made in G.Britain by Brimar (1960s).
Brown base, round plate, Bottom D-Getter. 
Very nice tubes from UK. Very warm and immediate sounding. 
One of the nice 6SL7s ever made from EU. All same date code
Nos but no original box. Packed in white box. Matched pair are available.

Made in USA by Sylvania.

Round muddy black plate, Bottom D-Getter.

Nos in original box.

Made in USA by RCA.

Round muddy black plate, Bottom D-Getter.

Nos in original box.

Made in G.Britain by Mullard (1950s).
Black base, short round plate, Bottom D-Getter. Similar 6SL7GT.
Can bring to you the superb sound, the best overall.
One of the best 6SL7s ever made.
Nos in original box.

Made in Holland by Philips.
Brown base, short round plate, Bottom D-Getter. Similar 6SL7GT. 
Great tube, super detail and balance sounding.
One of the best 6SL7s ever made.
Nos in original box.

Made in USA by RCA (1960s).
Muddy black plate, Triple mica and Double D-Getter with five supports.
Most of muddy black plate version are made by RCA.
Very warm sweet sound, great on voices and jazz. Long life tube (10.000 hours)
Nos in original box. Matched pair and quad are available.

Made in USA by RCA (1960s).
Muddy black plate, Triple mica and Double D-Getter with five supports.
Most of muddy black plate version are made by RCA.
Very warm sweet sound, great on voices and jazz. Long life tube (10.000 hours)
Nos in original box. Matched pair and quad are available.

Made in USA by RCA.

Round muddy black plate, Smoke glass. Bottom D-Getter.

Nos but no box. Packed in white box.

Made in USA by RCA for Western Electric.

Round muddy black plate, Bottom D-Getter.

Nos in original box.

Made in Sweden by Standard Radio under RCA's licence (1950s).  
Dark brown base, Muddy black plate included five supports around the plate, No hole on plate, Triple mica and double D-Getter.
One of singular of Swedish tubes ever made. One of the top 6SL7s in the world.
Nos, Never been used. Matched pair and quad are available. See more picture