After replacing broken buckles on both my TUSA
Imprex and Scubapro Twin Jets, I finally popped for
a set of spring straps. It is one of my best purchases
ever. I’d first seen these unique after-market straps on
California dive boats and realized that their sleek
design, attaching directly to the fin with no
buckles, would be resistant to catching on
kelp. Then I discovered added bonuses.
 Wearing my tank, BCD, and weight belt,
  supporting myself at the exit gate with one
  hand and pulling on each fin with the other
  was tough. (I’m not one of those silly people
  who walk across a dive boat deck with my fins
  on and I’m sure you’re not either.) However,
  my spring straps slide on and off with little effort.
  Because they compensate for the compression of
  boots at depth, they keep my fins secure and comfortable
  whether I’m wearing 7-mil boots or tropical
  slippers. Unbreakable springs mean you won’t lose a
  fin to a snapped strap. And a protective sleeve around
  the coiled steel keeps them from chafing.
Wearing my tank, BCD, and weight belt,
  supporting myself at the exit gate with one
  hand and pulling on each fin with the other
  was tough. (I’m not one of those silly people
  who walk across a dive boat deck with my fins
  on and I’m sure you’re not either.) However,
  my spring straps slide on and off with little effort.
  Because they compensate for the compression of
  boots at depth, they keep my fins secure and comfortable
  whether I’m wearing 7-mil boots or tropical
  slippers. Unbreakable springs mean you won’t lose a
  fin to a snapped strap. And a protective sleeve around
  the coiled steel keeps them from chafing.  
John Bantin, technical editor of Britain’s Diver
  Magazine, found another advantage while testing Apollo
  Spring Straps. “During finning the pressure of the
  springs pushed my boots further into the foot-pocket of the fins, so that they really felt like extensions of my
legs.” That fit, plus added stability and reduced drag,
makes some divers feel that spring straps improve the
performance of their fins. I can’t vouch for that, but for
comfort and convenience, they’re a winner.
There are several brands on the market, and many,
  like the XS scuba line, can fit a wide range of fins. Be
  sure they fit your fins and feet. Some models feature
  pull loops or grips, rubber or nylon spring covers, heel
  pads (some in a choice of colors), or quick release
  buckles (if you think you need them).
Expect to spend from $65 to $95 a pair. That’s steep,
  but these straps will probably outlast your fins. Many
  models are challenging to install, so it makes sense to
  buy them from a dive store that can attach them. Fin
  marketers Apollo and Scubapro have their own lines of
  straps. For comparison shopping, go to Leisure Pro’s
  selection at www.leisurepro.com and search for “spring
  straps.” Most manufacturers have their own websites
  with more information and local dealer listings.
Do-it-yourselfers can get instructions for making
  their own at:
www.cisatlantic.com/trimix/fins/sprstrps.htm
  www.scubase.net/pers/FinStraps.html
 – Larry Clinton