Adox XT-3 is an improved version of XTOL, and unlike XTOL you can buy it in 1 litre packs. The last batch of XTOL I mixed lasted only 2 weeks before it was useless, and I had to throw out 4.5 litres of the stuff. XT-3 is said to last at least 6 months after mixing, but I usually go through a 5 litre pack in three to four months. And if you decide on HC-110, Adox sells the original mixture made by the factory in the US that used to make it for Kodak in the old days. I hear that HC-110 users are unhappy with the new version from Kodak.