Christmas shopping has always been a numerical science: What size? How many? How much money? Buying has been pretty much by the numbers.

Lately, however, it would appear that Holiday shopping is more and more, to the letter: L.E.D… GPS… USGA…

In an attempt to spell out a few ideas, here are a few items that are selling this season.

Liquid Assets

America has become a hydration nation of water-conscious athletes, but potables must be suitably portable.

Jordan Ayers of Omega Sports in the New Hope Commons Shopping Center in Durham said the store’s Tervis Tumblers are some of the more popular buys this Christmas, and among featured store items selling for less than $20.

“They’re double-layered,” Ayers explained, “and they keep hot things hot and cold things cold.”

Likewise, Chad Pickens, manager of the Great Outdoor Provisions Company in Chapel Hill’s Eastgate Shopping Center, said water bottles were worth their weight in, well, water.

“Hydroflasks are the insulated water bottles,” Pickens said, “and they’re my favorite items in the store … one of a few super-hot items right now."

They range from $19.99 for the smallest up to a 64-ounce growler for $49.99, keeping liquids at the preferred temperature for 24 hours.

Let There be Light

As days grow shorter and darkness takes its toll on fitness options, athletes must shed a little light on the subject, and with improvements in LED technology, it’s getting easier to see how.

“When I first started the store in 1998, Petzyl (headlamps) came with this huge battery pack, and you’d go through your batteries in about three hours," Pickens said. “Now, you can get 185 hours out of them on three triple-A batteries.”

Next door to Great Outdoor Provisions Company, customers at Performance Bicycle in Eastgate Shopping Center are similarly seeing the light.

“Were selling a lot of the bicycle lights right now,” Performance’s John Bigelow said. “It used to be that folks would spend around a dollar per lumen, and it’s come to where I have 500 lumen lights for around $99.”

“No matter where you go, there you are.”

For those who need a bit more direction, there’s now GPS, which seems to be everywhere.

“Garmin has a new item,” Fleet Feet Carrboro store apparel manager Amy Jones said. “The Garmin Forerunner 10 ($129.99) has a little bit smaller face on it, so it’s a little more popular with women. It offers a virtual pacer so that you can make it pace you while you’re running, and it also offers interval timing, all in one watch.”

Golfers not currently on the PGA tour are all about any technology that can get them closer to the cup.

Adam Tucker of Golf Galaxy in New Hope Commons said this year’s choices are more about improvement to existing technology than new hi-tech items. Units can be wireless and voice-activated.

“You click a button and it tells you how far you are from the pin or from the green," Tucker said.

Warmest Regards

Athletes are bundling up more than their phone and cable services.

“Nike has some Shield pieces with vests and jackets for more wind protection,” Fleet Feet’s Amy Jones said. “We’ve already had some days starting out in the low 20s, so folks are gearing up.”

The vests start at around $80, while the full jacket with a hood runs around $250.

Bigelow at Performance Bicycle said: “People are layering with warm clothing, and gloves are huge too.”

Great Outdoor Provisions’ Pickens said wool base layers, called NTS (or "next-to-skin") doesn’t itch. "And you can launder it at home in your own washer and dryer.”

Many athletes prefer to surround themselves in room temperatures.

“Treadmills and elliptical are always selling,” said Jason Fearrington of Play It Again Sports on New Hope Commons Drive. “It’s getting cold outside, and folks need a way to work out without being outdoors. Ping pong tables are also going well right now.”

Golf Galaxy’s Tucker said golf can now be an indoor sport as well, with the year-round Optishot Golf Simulator, $349.95 (less a $50 mail-in rebate).

“Indoor soccer supplies are selling well,” Omega’s Ayers said, though he wasn’t sure if it was merely a fashion statement. “A lot of the kids are just wearing the shoes to school though, because they’re colorful.”

A Matter of Course

Buyers are looking past the Holidays to greener pastures (and fairways).

“TaylorMade RocketBladez Irons are popular,” Golf Galaxy’s Rob Schwarz said, “and they just came out. The graphite irons are $900 and the steel are $799. We also have Titleist ProV1 (balls) for just $39.99 a dozen.

For those not afraid to drive in ice or snow, there’s the Titleist 913(D2) driver.

“TaylorMade just came out with an adjustable driver,” Schwarz added, “and you can actually change the lie angle on that one.”

Frisbee golf poses a cost-wise alternative, and ultimate Frisbee supplies are also popular.

“The 175-gram Frisbees: those are selling a lot,” Play It Again Sports’ Fearrington said.

Both Fearrington and Omega’s Ayers wais disk golf supplies were selling well.”

Big Ideas; Little Packages

For those already putting the finishing touches on shopping, here are a few stocking stuffers to note:

At Omega: “Nike Elite Socks sell like hotcakes … and LED mini-lanterns work great for camping.”

Fleet Feet: Christmas tree ornaments; (bumper) stickers; headbands for women; variety packs (three pairs for $30) of Balega sock.

Great Outdoor Provisions: "Little Hotties” handwarmers, made in Durham.

Golf Galaxy: “A sleeve of balls is always a good stocking stuffer.”

Play It Again Sports: Pocket Disks — $10, $15 or $20 depending on size.”

Only 20 shopping days remain until Christmas, so days are numbered but the gift ideas are lettered. As hectic as the holidays are, here’s hoping the spirit still weaves its spell on you.