I have a set of both Dura's and AFS.
Completly different aspects with each kind.
Dura's are great for basically "flat" blocking and do have "some" flex BUT,
Do NOT expect them to BE FLAT. Even straight out of the box,they need to be checked with a thick piece of glass,your assured of it being fairly "true" from a flat aspect,and need checking.SEE this posting.
ALL Durablocks ARE made for 2.75" roll,PSA paper, Never seen ANY with velcro attatchment.Actually never seen much velcro roll size paper. Some junk flat sheet for a air file but that was about it.
I recently got a complete set of AFS blocks and WOW,They are EXCEPTIONAL for ANY type of curved surface of ANY size.
If your planning on doing several projects or for a living,These are a MUST have. You can use all the rods for a stiff,flat block or remove them all for a superior flexable block which will stay TRUE to the contour. They are also for PSA roll paper and basically need no truing as they come flat and STAY flat unless you really get STUPID with them and like bend them double,drop them on the floor or something.
I got my Durablocks locally for a LOT less than Eastwoods but the AFS's came from TCPGlobal. Check around for the pricing for sure.