I like to keep a sleeve or two of my favorite ball from seasons past:
Titleist Professional Tour Ballata 100 one dz.
Wilson iWound two sleeves
TaylorMade Innergel two sleeves
Titleist HP2 Tour, DT wound, HVC and Ballata red 90 two sleeves ea.
Top Flite Strata Tour 90 two sleeves
Maxfli "Elite" one dz.
Callaway Chrome+ 1.5 dz
Taylormade Penta 5, LDP Red one dz.
TaylorMade Pref X one dz.
TaylorMade Pref one dz.
Does anyone else miss the sound and feel of a wound ball? I sure do!