Bought these tuners to install on my Messer Blues resonator. They are designed especially for slotted headstocks as the holes in the barrel are set in the middle of the shaft, not at the top. They would not fit a standard 3 a side headstock.
Although Grover ceased production in the USA many years ago, these Chinese made tuners work well. They all have a solidly consistent feel when turned and the 1:15 gearing gives stability and accuracy when tuning.
They look aesthetically pleasing, and most importantly, function well without any slipping. They are solid, reliable and get the job done. For the asking price, they represent good value, and should last a lifetime.
Would certainly buy again.