Are These All Precancelled? Even The Stamped Envelope?

I have this cover with 2 stamps on a stamped envelope all with MASON MI cancel. I am assuming the cancel is a precancel and it looks like all are precanceled. Thoughts? I tried to crop this several times and several ways but each time the right side would be cutoff when I went to save it.

Yes, they sold precancelled envelopes to non profit agencies.

The 1.25, 1.4, 1.6, and 1.7 envelopes of this liberty bell design correspond to the non-profit bulk mail rate as it gradually increased over time. The unprinted wavy lines within the design are the precancel, as would be expected on this class of mail. There was no need to apply the handstamped precancel onto the basic envelope. No doubt this is a collector-inspired philatelic mailing uprated to the 10 cent letter rate, likely containing a newsletter for a precancel organization.

Thanks John! I figured it might be a philatelic cover. Just wanted to be sure. I will be listing it on my eBay site soon.