recently I've been testing a lot of different parts for my worker caliburn v3.
I've tested multiple printed plungers as well as the worker aluminum plunger and I have to say, the acetal plunger is by far the best I have tested.
I achieved 100% air seal without any modification or added Teflon tape to this plunger and it has much less friction in the plunger tube than all my other plungers as well . just drop it in and your good to go.
For muzzle velocities i picked up ~10-15 fps over the stock printed worker plunger, which pushed me just over the 300 fps mark at 302 fps over a 12 shot test group.
overall id say this is a must buy if your looking to get get the most efficiency out of your caliburn.