NKT/NLT Red Dot Fuzz. (See errata)
Analog Mike on this specific Red Dot. This pedal is labeled an NKT 275 however the exact transistor is described below. Nothing mentioned about NLT and NKT perhaps the nomenclature is as described. The Analogman has this photo and is documented in the Variations of high quality Newmarket Transistors.

In mid 2017 we got some red dot NKT transistors which are not the 275 model, from a source in The Netherlands. These are definitely made at the Newmarket factory over 40 years ago, and look and sound almost identical to the red dot NKT275 we used to have. They test in the same range, medium low gain. I think they came from the same manufacturing line as the NKT275, but were sorted for this narrower gain range. They have a different part number on them after the "NKT", probably a house number for the specific customer who requested these parts (maybe a radio company in the Netherlands). We ran out of these in 2020.

Here is the description of Red Dots which is what the pedal is after reading above.
Red Dot NKT275 transistors We also had gotten a large batch of "red dot" NKT275. These don't look identical to the original ones, they may have been be relabeled but have similar specs. These are not quite as clean or clear sounding as the white dot. The red dot do not get as sparkly clean when you back down the volume, but they have a longer, smoother range when backing down the volume knob so it's easier to find just the right amount of fuzz. They have a cool smoky, bluesy tone, a little softer and darker. They definately have some MOJO in the sound. They are a little more finicky and tougher to dial in, especially at various temperatures, so the sundial has a WIDE range on these. We ran out of these again in late 2015.

I can attest that these clean up but do not sparkle, they have a bitey edge on the higher frequencies. Lots of dynamic range when using tone control.

Errata: M/L medium low gain denoted on the pedal. NLT is NKT just a Mike Piera handwriting nuance with the K.