I learned most 6" Celestron telescopes are factory compatible with the Hyperstar and come with a knob you can grasp to pull the secondary out after you remove the retaining ring. Then it fits nicely into the little can that you remove from the Hyperstar before inserting the Hyperstar in place of the secondary mirror. Then the retaining ring screws onto the can so the secondary mirror can be safely stored while the Hyperstar is in use.
However, I purchased my Celestron 6" separately from other equipment and it had no knob for me to grip to slide out the secondary after removing the retaining ring. If you look closely at the following image, you will see that there is a serial number stuck on my secondary mirror back plate where most C6’s have a knob.
Now, here is a word of caution. Do NOT try to replace the plate when the secondary mirror is still in place on the C6! You must remove it from the C6 to perform the simple modification procedure.
To begin, keep the telescope tilted slightly up, carefully unscrew and remove the retaining ring. The following picture shows that the lip of my secondary mirror plate sits flush and it would be very hard to remove just using your fingers.
Note the location of the side index screw. Then carefully remove the top 3 screws and remove the plate from the mirror. Use the new screws provided to attach the new plate with the knob, with its side index screw in the same orientation as shown below.
Starizona also recommended when installing the new plate to adjust the new screws so the plate is approximate parallel to the secondary mirror to make it easier to collimate later. When you first attach it, just lightly screw the new plate in place. Then look at it from the side and adjust the screws until it is approximately parallel (loosen other screws before screwing one in further). Having it about parallel to begin with means it doesn’t take much adjusting once installed on the telescope to collimate it.
In the following picture, the secondary mirror is now back in place and shows it now has the new plate w/knob, just like most standard factory C6 telescopes.