Early external frame pack boards were made from wood or solid metal, then came the aluminum. The innovators at Alpine Designs saw a new progression in this pack made of a PVC plastic frame. It’s definitely one of the most unique external frame packs I’ve encountered, and probably for good reason. The use of plastics instead of aluminum seems to save no weight at all (if not adding some). It’s also hard to imagine this plastic could withstand the stresses, shock and temperatures of an aluminum frame. Still this pack has survived rather well with no cracks and all plastic hardware intact.
Regardless of materials, this pack is very well constructed with plenty of details that make it Alpine Designs. Leather zip assist tabs, integrated pack handle on the frame, and innovative lace loops to secure the top hatch to name a few. This pack also features very thinly padded shoulder and waist straps. It has no lashing squares but does have two pair of D rings on the underside.
Pack make-up includes:
1 top entry main compartment
1 front entry second main compartment
2 top entry side canister pockets
2 front entry secondary side canister pockets
1 small front entry compartment on the outside of the secondary main compartment.
Basecamp Vintage & Archives 
I also own this backpack, although it’s blue. I still remember when the guy at the store picked it up and threw it down on it’s frame. It just flexed and was undamaged. The idea was that it wouldn’t break or bend like an aluminum frame if you accidentally dropped it and it was supposed to flex with you when you moved. It is still in great shape and I still use it. I also have their sleeping bag (green poly filled) and it still keeps me warm on cold nights. They made good gear.
I had a pack just like this one back in the early 90s I gave it to the brother of a freind of mine ,would love to have another one like it just for old time sake. great pack.
A year later …. John, I have one I just put on CL – Yakima if you’re still looking.