Things I liked: The hardest hitting .25 caliber pellet that is currently available without resorting to making your own. These are the 2nd most accurate in my .25 Condor, once I get them moving fast enough. High energy is retained to any distance you are capable of shooting with an air rifle.
Things I would have changed: I would reduce the diameter of the head by .002", but that may make them worse for the Sumatra. Would be nice to get tins of at least 200 for the same price.
What others should know: These are the same pellet as the Eun Jin 42 gr pointed, but they wear the SAMYANG label. These heavy pellets need to be pushed into the 900fps realm to really show what they are capable of. These pellets will require a very heavy backstop as they shoot through 1.5" of wood quite easily. If used for hunting, be aware that complete pass through of the target is almost 100% of the time.
Things I liked: Green dot is easy to see out to 100+ yards even in bright sunlight. Pressure switch is easy to use, does not require much pressure. You can depress it easily without disturbing your grip on the gun.
Things I would have changed: Refine the adjustment system. The adjustment screws move the beam too quickly, and are too easy to turn. 1/2 turn on the elevation screw moved the beam 14" at 60 yards. Add an optional mount for 3/8" or 9-11mm rails. Make the housing lighter.
What others should know: This unit is beefy, it weighs a bit more than it looks like it should. The rear mount screw requires a wide slot in the picatinny rail, I had to widen the slot on my weaver rail. Uses a fairly expensive "N" type battery, but comes with one. Packed in a nice tin box with a foam insert which I used for a little airgun toolkit box.