Kluson K33 Keystone Guitar Tuning Machines 3-Per-Side Nickel 3-per-side Completely sealed Keystone button Double row casing print TonePros Kluson K33 guitar tuners are classic 3-per-side vintage style, but with TonePros engineering technology packed into the vintage box TonePros is first in the industry again with "33s" completely sealed tuner technology applied to the vintage "Press In Bushing" format This means that these tuning machines do not have the hex bolt around the tuner post of more modern tuners, yet these tuners are uniquely designed with extra post support and are very tight and exact in both tuning directions 33 series tuners do not require the large hole size of either of the more modern tuners