Ditto dive-aholic!!!!
The very first minute your nitrox card is minted, you have to buy your own annyliser.
If you trust the one at the fill station that gets dropped twice a day, calibrated by idiots, operated by the shop owners stoned son, you are rolling the dice.
True story I am on dive vacation sunny florida, shop does partial pressure blending, I get my tanks filled, he asks do you want me to annylise that? I say no, I have my own. He replys good! ours is on the fritz, you have to bang it to get it to work right.
I then watched 5 people get fills, bang the annyliser, sign the log, and go diving.
Sorry not me.
Eric