Anti-turtle Sleeves

How effective are the silicone anti-turtle sleeves when it comes to jelqing? I have been reading about the ones they sell on Zen. Been having issues with turtling on and off. Currently at just barely shy of 7.5 BPEL and 5 5/8” mseg and not really seeing much growth if any. Just wondering if having an anti-turtle sleeve will help to cement any growth from my PE routine. Other issue is wondering if their largest 1.5” diameter sleeve would be okay, I am pushing 1 and 7/8” diameter hard, should I try going with say the 1” diameter since it will be used soft or would the larger 1.5” or the 1.25” be best since it will be applied hard for the beginning of use? Thoughts, thanks in advance.