shuttle speed

hi guys,
is there any rating of the shuttle speed that is used in
professional levels.i have not used yonex shuttles becoz they are not available in my place(rather i have not found em).i get to use different shuttles but i have not kept track of all of them.

the way i feel/test the speed is stand on the baseline of a court
and hit flat hard(quite hard) drive straight.if it falls before the doubles service back-line i consider it good.i just picked this idea from a professional player.

i get to use EPSILON often as it seems to be a popular brand in my place.i have seen different speed ratings like 49,50,51 etc.

49 is the slowest which my friend told me was similar to professional players use.i use 50 and iam not sure if i have played with 49.

then i got to play with RSL tournament shuttles which my friend got from malaysia.They were real slow and they were not durable.
within a few hits the shuttle's flight was shocking.


i have played with indonesian shuttles (dunno the brand)and they were slow as well.

the other day i played with RSL Tourney shuttle and they were slow as well and durability was shocking.i was struggling to time the shuttle.


So, iam really confused as i see guys on this board using i think
official yonex shuttles but have not seen any discussion on speed.

The point is if one plays regularly with a slow shuttle and u switch to a slightly fast shuttle it should be ok,but vice-versa
it would be hard to switch to a slow shuttle becoz of the need to
impart more strength.

So, is there a uniform way of judging shuttle speed across different brands so that u could play with the same kind of shuttle all the time.

sorry for the lengthy post.