Hi IR:
Envigo is gone in name only! The company that owns the name is Inotiv and they are not new and still in business! What Inotiv did following the Beagle Abuse Scandal was change the "brand" name of the Blocks from Envigo (and before that it was Harlan- Teklad) to just plain "Teklad." They still carry the same Blocks. Here is a link to their Info Site;
https://www.inotiv.com/rodent-natural-ingredient-diets
Teklad 2018 is offered on Amazon and I have pasted a Link for a site with 84% 4-star reviews; but I still have a frozen stash and have not yet tried these Blocks from Amazon. Here is the link;
https://www.amazon.com/Envigo-Former...39&sr=8-7&th=1
I used to use the eBay merchant, Ecosandy as a source for just about any quantity or variation of Teklad Rodent Blocks but she has NOT been offering these in quite some time!
As far as the Mazuri, if you don't mind a suggestion; the specific variety of Mazuri Blocks that I have used in the past is Mazuri Rat and Mouse Diet and while Mazuri does not provide the detailed breakdown of the nutritional components as does Teklad; the Mazuri Rat and Mouse Diet contains 23% Protein and for a young Squirrel or a young adult Squirrel, this percentage of protein is just fine. For a relatively "senior" Pet or NR, I would not really recommend this amount of protein as it may potentially have an adverse impact on kidney function and for those Squirrels I would suggest Teklad 2014 (2018 contains approximately 18% protein and 2014 contains around 14% protein).
Regards,
SamtheSquirrel