They have a 1500+ page catalog viewable online as well as a monthly sale flyer. It's a pain in the ass to view the catalog online & as you know not much of their inventory is cataloged on their website.
They have been saying their website is going to be updated so perhaps they are working on it but it has been quite sometime that they have been saying the website will change. Not an easy job to catalog everything if that's what they are doing.
Perhaps you can call to order a paper catalog, i have never noticed a way to order one online. IIRC they do include their sales flyer with every shipped order.
You can download the entire catalog if you want. From the "on-line catalog", look at the tool bar on the bottom and there is an icon with an arrow pointing down. Click on it and it will download the entire catalog as a pdf. Note that for the impatient. It is half a gig so "its going to take a while" applies.
You might also try a PowerShell command [or wget if you are on ?nix]. Probably will not be any faster but it save the browser from having to start Adobe to display the pdf. The url is pretty straight forward ... "http://allindustrial.com/catalogs/2016/general_catalog.pdf".