So just got my two Alpha starting clamps / string extender tools the other day and strung about 4 rackets with them. Love the clean simple minimalistic look. The surface of both rough and provides excellent grip but I can see some people not liking it over some sort of rubber or smoother/softer. Maybe lead to more dry skins in grip areas XD
Didn't expect them to be so small (refer to picture)
While also being small surprisingly light weight.
Yonex Starting Clamp Clone was only
137.7g and the other starting clamp
87.8g. My 3 spring clamp was
165.7g.
Now the pull test, the Yonex Clone works as expected. I found it was way smoother to lock and surprisingly easy to unlock as well, not to the point where you would be afraid of it suddenly release but way more easier then the Yonex starting clamp. The lighter weight made it more of a pleasure to use for knotting.
The two spring starting clamp definitely has less clamp force then my 3 spring but. But the gripping surface was much rougher and the weight savings was definitely worth it for me. Was gonna primarily keep it free of string extenders but I would feel fine using it as an extender after stress testing it. It doesn't really punish you if you don't put the string deep enough into the clamp unless your pulling 28lbs+ on the thinner strings (aerosonic, kizuna z58, exbolt 63).
Tested strings / tensions until slippage with string slight above or under the holes. Strings that are italicized notice slippage unless clamp below the holes / show signs of slippage & stripping of coating / slipped twice in about 8 test pulls.
BG-65 / BG-65ti / Zymax 69 fire / G pro 70 - 35lbs + 10%
Exbolt 65 / BG-80 35lbs + 10%
NBG98 34lbs + 10% (gotta really make sure string is in the right spot for higher tension)
Exbolt 63, Aerosonic, 33lbs + 10%
Kizuna Z58 32lbs +10% (string snap at fixed clamp 3 times in 9 pulls)
Note: some of the more durable strings could probably be pulled higher and the clamp most likely will hold, I'm just too scared to try.
Overall they are pretty pricey and as Darth said if you can afford the Yonex one I think its well worth to have if you only plan to have 1 starting clamp. But for 1/4 savings you can have these two which I think are just as good.