Handle Variations

AJ Link - This style has a metal loop welded to the jack, and the wrist strap is on a D Ring.

The advantages of this style

• Easy to fold for pocket carry
• Allows a certain amount of twist, should someone grab the jack and twist it to force you to the ground the extra twist allowance greatly reduces this
• Often seen on mid 20th century American jacks. Th attachment into the spring on those is usually a swivel

2 Part - traditional style, wrist loop is one part, and fixed to the jack shaft, then over braided. This is the classical look often seen on the late 19th and early 20th century jacks

Often seen on early examples the leather tends to deteriorate and then snap off, so early jacks just appear to have an enlarged braided end, as this is all that remains. 

Advantages of this style

• This style is easier and quicker to slide your hand through over the AJ link.
• It does add abid of security in dropping it compared to no strap.

Disadvantages

• These do take a while to soften up so pocket carry can be a bit awkward.

Pinky Loop - A short leather loop sized big enough for the average pinky finger

Advantages of this style

• Small and doesn't flap around or get in the way
• Very little protrudes from the pocket so less obvious
• Quicker to use when faced with a situation and you need to use the jack, no having to stop and put your hand through the standard style wrist loop

Polo Grip Loop (or Carnie strap) - Extra Long '2 Part' style loop, this goes over your thumb and back of the hand.

Adantages of this style

• Locks the jack in a firm fixed grip 
• Reduces nearly all looseness in the grip, so if you have a weak grip this is probably the best style
• Reduces grip fatigue when using the jack

Over back of Hand Strap - Fitted to the DL Convoy and the Head Wrap (HW)

Advantages of this style

• If you have a weak grip, for any reason, age or disability, then these are probably the best. The weight of the lead can cause the jack to extreme momentum and if you aren't gripping it tight enough, out your grip it will continue
• Not easily removed from your hand by an assailant 

Disadvantages

• Less flex is felt