This Spikesender23  (locking button) fits: 
 
Panther; Alloy & CF
Distel; Alloy & Classic
Gecko; Alloy & CF
Notch; Alloy & CF 
 
This SS23/LB  DOES NOT fit:
 
*New Distel CF: Shank is too wide.
*Notch Steel: Shank prevents locking button use.  
For the above models hit this LINK  SS23/RR
 
*New Distel MK3 alloy or Distel DMM: These have ribbed shanks that require a Spacer to be placed behind the SS23 to fill the void. NOTE, doing this will drastically change the dynamics and feel of your gaffing as the gaffs will protrude a further 10mm toward the tree. Using 'short' or 'pole' gaffs would mitigate this change in feel. 
 
 
 
 
 
Spikescender23- The original. A world first made by KK in 2013.
This Spikesender has an optional locking button. It's up to you whether you secure the rope in place for a long ascent or not for a quick 'leg up' and then pop it out without using your hands!
 
The KK Spikescender bolts directly to the shaft, beneath the existing gaff, and tucks well out of the way beside your heel. The use of the KK Spikescender ensures smooth management of slack, while keeping your climbing line well out of harms way when ascending SRT or MRT. Milled from aircraft grade aluminum and featuring a titanium toothed cam, the KK Spikescender runs far smoother than any of the other foot ascender brands currently on the market. Dale has lightly tensioned the Titanium cam which seems to resist the tendency to create a bight in the rope on ascent. KK Spikescender can only be used when attached to stirrups.